Use of electromagnetic field for tomographic imaging of head

ABSTRACT

An electromagnetic tomographic scanner, for use in imaging a live human body part, includes an imaging chamber, a plurality of antennas, a controller, a lid, and a quantity of matching media. The imaging chamber is supported on the base, defines an imaging domain in that receives the head, and has an open end. The antennas are supported by the imaging chamber and encircle the imaging domain. The controller controls one or more antenna. The lid is attachable to the open end and includes a hollow boundary model that mimics a part of human anatomy that is outside the imaging domain. The matching media fills the interior of the model while an empty field measurement is carried out. Various tensors may be produced.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a U.S. continuation patent application of,and claims priority under 35 U.S.C. § 120 to, U.S. patent applicationSer. No. 16/536,887 to Semenov, filed Aug. 9, 2019, which '887application published as U.S. Patent Application Publication No. US2019/0357803 A1 on Nov. 28, 2019 and issued as U.S. Pat. No. 11,350,842on Jun. 7, 2022, which '887 application, the application publicationthereof, and the patent issuing therefrom are each expresslyincorporated herein by reference in their respective entireties, andwhich '887 application is a U.S. continuation patent application of, andclaims priority under 35 U.S.C. § 120 to, U.S. patent application Ser.No. 16/420,543 to Semenov, filed May 23, 2019, which '543 applicationpublished as U.S. Patent Application Publication No. US 2019/0274578 A1on Sep. 12, 2019 and issued as U.S. Pat. No. 11,253,164 on Feb. 22,2022, which '543 application, the application publication thereof, andthe patent issuing therefrom are each expressly incorporated herein byreference in their respective entireties, and which '543 Application isa continuation of, and claims priority under 35 U.S.C. § 120 to,International Application No. PCT/US2017/63169, filed Nov. 23, 2017,designating the U.S., and entitled “USE OF ELECTROMAGNETIC FIELD FORTOMOGRAPHIC IMAGING OF HEAD,” which '169 application published as WO2018/098387 A1 on May 31, 2018, which '169 application and theapplication publication thereof are each expressly incorporated hereinby reference in their respective entireties, and which '169 application,for purposes of the United States, is a U.S. nonprovisional patentapplication of, and claims priority under 35 U.S.C. § 119(e) to, U.S.provisional patent application Ser. No. 62/426,101, filed Nov. 23, 2016and entitled “USE OF ELECTROMAGNETIC FIELD FOR TOMOGRAPHIC IMAGING OFHEAD,” which '101 application is expressly incorporated by referenceherein in its entirety. In addition, each of the following patents,patent applications and patent application publications is incorporatedby reference herein in its entirety:

-   -   (a) U.S. Pat. No. 9,414,749 to Semenov, issued Aug. 16, 2016 and        previously published on Jun. 5, 2014 as U.S. Patent Application        Publication No. 2014/0155740 A1, which is intended, at least, to        provide background and technical information with regard to the        systems and environments of the inventions of the current patent        application;    -   (b) International Publication No. WO 2017/066731 A1, which was        published Apr. 20, 2017 based on International Patent        Application Serial No. PCT/US2016/57254 to Semenov, filed Oct.        16, 2016 and entitled “ELECTROMAGNETIC INTERFERENCE PATTERN        RECOGNITION TOMOGRAPHY,” which is intended, at least, to provide        explanation of pattern recognition techniques and their        application to electromagnetic tomography; and    -   (c) U.S. Patent Application Publication No. 2012/0010493 A1,        which was published Jan. 12, 2012 based on U.S. patent        application Ser. No. 13/173,078 to Semenov, filed Jun. 30, 2011        and entitled “SYSTEMS AND METHODS OF ELECTROMAGNETIC TOMOGRAPHY        (EMT) DIFFERENTIAL (DYNAMIC) FUSED IMAGING,” which is intended        to provide background and technical information with regard to        4D EMT imaging.

COPYRIGHT STATEMENT

All of the material in this patent document is subject to copyrightprotection under the copyright laws of the United States and othercountries. The copyright owner has no objection to the facsimilereproduction by anyone of the patent document or the patent disclosure,as it appears in official governmental records but, otherwise, all othercopyright rights whatsoever are reserved.

BACKGROUND OF THE PRESENT INVENTION Field of the Present Invention

The present invention relates generally to electromagnetic tomographyfor imaging a human head, and, in particular, to the use of improvedmatching media formulations, localized antenna control circuitry,simultaneous data measurements, improved EM fields calibration, andimproved normalization techniques in systems and methods ofelectromagnetic tomography for imaging a human head.

Background

Electromagnetic tomography (EMT) is a relatively recent imaging modalitywith great potential for both biomedical and industrial applications.Biomedical applications include but are not limited to the non-invasiveassessment of functional and pathological conditions of biologicaltissues. Industrial applications include but are not limited to oil andgas exploration, mine search and assessment, and flow assessment withinnon-metallic pipes. Using EMT, objects such as biological tissues aredifferentiated and, consequentially, can be imaged based on thedifferences in the dielectric properties of such objects. EMT isbelieved to have high potential for biomedical applications based on therecent demonstration of the dependency of tissue dielectric propertieson the tissue's various functional and pathological conditions, such asblood and oxygen contents, ischemia and infarction, stroke,malignancies, edema and others.

Two-dimensional (2D), three-dimensional (3D) and even “four-dimensional”(4D) EMT systems and methods of image reconstruction have been developedover the last decade or more. Feasibility of the technology for variousbiomedical and industrial applications has been demonstrated, forexample, for cardiac imaging and extremities imaging.

As in any tomographic imaging, the classical EMT imaging scenarioconsists of cycles of measurements of complex signals (for example:amplitude and phase), as affected by the presence of an object understudy located within a so-called imaging domain, defined by an imagingchamber, as produced by a plurality of transmitters located at variouspoints around the object and measured on a plurality of receiverslocated at various points around the object. This is illustrated in FIG.1, which is a simplified schematic illustration of portions of anelectromagnetic tomography (EMT) system. The locations of thetransmitters and receivers may be within the imaging domain, on theboundary of the imaging domain, or outside the imaging domain. Themeasured matrix of EM signals may then be used by a data processingsystem in image reconstruction methods in order to reconstruct 2D or 3Ddistribution of dielectric properties of the object, and thus, a 2D or3D image of the object, which for biomedical applications is typically ahuman body or part of a human body, such as a head, a torso, an arm orthe like, but may also be any object without metal shielding.

Generally, it is very important for image reconstruction to preciselydescribe a distribution of an EM field within the imaging domain. Thedistribution of an EM field within an imaging chamber is a very complexphenomenon, even when there is no object of interest inside. The use ofEM fields for imaging inside of a strongly shielded object (but notmetallically shielded) is a problem of even higher complexity. Oneexample of such an application is imaging of the human brain, but itwill be appreciated that other such applications of this type mightinclude imaging of any human tissue that is shielded by a bonystructure. The EM imaging of the brain or other tissue surrounded bybone presents a very complicated, high dielectric contrast problem. Thechallenge is to reconstruct hidden properties of deep brain tissueswhich are effectively shielded by a high dielectric contrast shield,comprising the skull (with dielectric properties in a range of 16+j5)and the cerebral spinal fluid (with dielectric properties in a range of60+j30).

EMT imaging of high dielectric contrast objects, including biologicalobjects, involves the problem of so-called “diffraction tomography.”Although such problem is difficult, mathematical algorithms andcorresponding systems and software implementations have been developedthat proved to be very reliable and delivered images of objects ofdifferent sizes from a few centimeters in the excised canine heart up toa full-size body in 2D, 3D and 3D vector cases. However, suchdevelopments are still less than ideal when imaging inside of stronglyshielded objects.

More recently, the use of a new interference pattern recognitiontomography flow was introduced for generating an accurate representationof EMT imaging of objects that have a high dielectric contrast shield,such as but not limited to the human brain. However, the success of thisflow is dependent on accurate and precise measurements generated andreceived by the plurality of EM hardware devices used when imaginginside of strongly shielded objects, usually but not necessarilydisposed on the boundary apparatus. Further improvements, involvinghardware, software, or both, are needed for accurately and preciselygenerating and communicating the EM signals transmitted and receivedfrom the EM hardware devices.

SUMMARY OF THE PRESENT INVENTION

Some exemplary embodiments of the present invention may overcome one ormore of the above disadvantages and other disadvantages not describedabove, but the present invention is not required to overcome anyparticular disadvantage described above, and some exemplary embodimentsof the present invention may not overcome any of the disadvantagesdescribed above.

Broadly defined, the present invention according to one aspect is anelectromagnetic tomographic system for imaging a human head, including:a base; an imaging chamber, supported on the base, that defines animaging domain in which a human head is received; at least one ring ofantennas, supported by the imaging chamber and encircling the imagingdomain; a plurality of antenna controllers, each antenna controllercomprising circuitry carried on a printed circuit board, wherein each ofthe plurality of antenna controllers is dedicated to a respectiveantenna in the ring of antennas, and wherein the circuitry of eachrespective antenna controller controls operation of the correspondingantenna and also provides, as output, data representative of measuredelectromagnetic field signals received by such antenna; and an imageprocessing computer system that receives, from the plurality of antennacontrollers, the output data representative of the measuredelectromagnetic field signals received by the respective antennas andderives image data therefrom.

In a feature of this aspect, the circuitry for each respective antennacontroller is carried on one or more dedicated printed circuit boardthat are separate from the respective printed circuit boards for theother antenna controllers. In further features, the circuitry for eachantenna controller includes radio frequency (RF) transceiver circuitrythat has a transmit side and a receive side that are alternatelyconnected to the antenna using an RF switch; the system further includesa plurality of antenna adapters, wherein each of the plurality ofantenna adapters is dedicated to a respective antenna in the ring ofantennas, and wherein the antennas and antennas adapters includecircuitry that is carried on a dedicated printed circuit board that isseparate from the respective printed circuit boards for the otherantennas and antenna adapters; the circuitry for each antenna andantenna adapter and the circuitry for the corresponding antennacontroller are carried together on a single respective printed circuitboard; the circuitry for each antenna and antenna adapter is carried ona first printed circuit board in a first module and the circuitry forthe antenna controller corresponding to the antenna and antenna adapteris carried on a second printed circuit board in a second module; eachrespective first printed circuit board module is connected to itscorresponding second printed circuit board module via one or more cable;the second printed circuit boards for all of the antennas are housedtogether in a location separate from the antenna rings; the plurality ofsecond printed circuit boards are arranged in a ring around the firstprinted circuit boards such that each respective second printed circuitboard is disposed adjacent its corresponding first printed circuitboard; the circuitry for each respective antenna controller includes ananalog to digital converter (ADC), carried on the one or more dedicatedprinted circuit board, such that the data representative of measuredelectromagnetic field signals received by the corresponding antenna maybe generated; the circuitry for each respective antenna controllerincludes a digital signal processor carried on the one or more dedicatedprinted circuit boards; the circuitry for each respective antennacontroller utilizes a superheterodyne technology-based architecture; thecircuitry for each respective antenna controller includes a radiofrequency (RF) transceiver stage that is connected to the antenna, anintermediate frequency (IF) stage that is connected to the RFtransceiver stage, and a baseband (BB) data processing stage that isconnected to the intermediate frequency (IF) stage; the baseband (BB)data processing stage produces the data, representative of measuredelectromagnetic field signals received by the antenna, that is providedas output; the intermediate frequency (IF) stage utilizes quadraturemodulation to produce an IF signal that includes both in-phase andquadrature components; a common clock oscillator is provided to theintermediate frequency (IF) stage of each of the plurality of antennacontrollers; each intermediate frequency (IF) stage includes a frequencysynthesizer, utilizing the common clock oscillator as input, thatprovides a carrier signal of at least 100 MHz for an analogmodulation/demodulation process; and/or the carrier signal provided bythe frequency synthesizer for the analog modulation/demodulationprocess, utilizing the common clock oscillator as input, is at least 1GHz.

In another feature of this aspect, the imaging chamber is cylindricaland includes at least three rings of antennas. In further features, theimaging chamber includes at least five rings of antennas; the imagingchamber includes six rings of antennas; and/or each of the at leastthree rings of antennas includes a number of antennas that is equal tothe number of antennas in each of the other rings.

In another feature of this aspect, the imaging chamber is semisphericaland includes at least three rings of antennas; the imaging chamberincludes at least six rings of antennas; and/or each of the at leastthree rings of antennas includes a number of antennas that is differentfrom the number of antennas in each of the other rings.

In another feature of this aspect, the imaging chamber translatesrelative to the base; the imaging chamber translates horizontallyrelative to the base; the imaging chamber translates vertically relativeto the base; and/or the imaging chamber rotates upward and downwardrelative to the base.

In another feature of this aspect, the antennas are waveguide antennas.

In another feature of this aspect, the antennas are slot antennas.

In another feature of this aspect, the image processing computer systemis integrated with the electromagnetic tomographic scanner.

In another feature of this aspect, the image processing computer systemis disposed in the same room as the electromagnetic tomographic scanner.

In another feature of this aspect, the image processing computer systemis disposed in a room that is different from a room in which theelectromagnetic tomographic scanner is disposed.

Broadly defined, the present invention according to another aspect is anelectromagnetic tomographic system for imaging a human head, including:a base; an imaging chamber, supported on the base, that defines animaging domain in which a human head is received; at least one ring ofantennas, supported by the imaging chamber and encircling the imagingdomain; a plurality of antenna controllers, each antenna controllercomprising circuitry, utilizing a superheterodyne technology-basedarchitecture, that is dedicated to a respective antenna in the ring ofantennas, and wherein the circuitry of each respective antennacontroller controls operation of the corresponding antenna and alsoprovides, as output, data representative of measured electromagneticfield signals received by such antenna; and an image processing computersystem that receives, from the plurality of antenna controllers, theoutput data representative of the measured electromagnetic field signalsreceived by the respective antennas and derives image data therefrom.

Broadly defined, the present invention according to another aspect is anelectromagnetic tomographic system for imaging a human head, including:a base; an imaging chamber, supported on the base, that defines animaging domain in which a human head is received; at least one ring ofantennas, supported by the imaging chamber and encircling the imagingdomain; a plurality of antenna controllers, each antenna controllerincluding radio frequency (RF) transmitter/receiver circuitry that isconnected to an antenna of an imaging chamber of an electromagnetictomographic scanner, an intermediate frequency (IF) stage that isconnected to the RF transceiver transmitter/receiver circuitry, and abaseband (BB) data processing stage that is connected to theintermediate frequency (IF) stage, wherein the baseband (BB) dataprocessing stage produces, as output, data representative of measuredelectromagnetic field signals received by the antenna; and an imageprocessing computer system that receives, from the plurality of antennacontrollers, the output data representative of the measuredelectromagnetic field signals received by the respective antennas andderives image data therefrom.

In a feature of this aspect, the radio frequency (RF)transmitter/receiver circuitry, the intermediate frequency (IF) stage,and the baseband (BB) data processing stage for each respective antennacontroller are carried on a dedicated printed circuit board that isseparate from the respective printed circuit boards for the otherantenna controllers.

Broadly defined, the present invention according to another aspect is anelectromagnetic tomographic scanner for use in imaging a human head,including: a base; an imaging chamber, supported on the base, thatdefines an imaging domain; at least one ring of antennas, supported bythe imaging chamber and encircling the imaging domain; a plurality ofantenna controllers, each antenna controller comprising circuitrycarried on a printed circuit board, wherein each of the plurality ofantenna controllers is dedicated to a respective antenna in the ring ofantennas, and wherein the circuitry of each respective antennacontroller controls operation of the corresponding antenna and alsoprovides, as output, data representative of measured electromagneticfield signals received by such antenna.

In a feature of this aspect, the circuitry for each respective antennacontroller is carried on one or more dedicated printed circuit boardthat are separate from the respective printed circuit boards for theother antenna controllers. In further features, the circuitry for eachantenna controller includes radio frequency (RF) transceiver circuitrythat has a transmit side and a receive side that are alternatelyconnected to the antenna using an RF switch; the scanner furtherincludes a plurality of antenna adapters, wherein each of the pluralityof antenna adapters is dedicated to a respective antenna in the ring ofantennas, and wherein the antennas and antennas adapters includecircuitry that is carried on a dedicated printed circuit board that isseparate from the respective printed circuit boards for the otherantennas and antenna adapters; the circuitry for each antenna andantenna adapter and the circuitry for the corresponding antennacontroller are carried together on a single respective printed circuitboard; the circuitry for each antenna and antenna adapter is carried ona first printed circuit board in a first module and the circuitry forthe antenna controller corresponding to the antenna and antenna adapteris carried on a second printed circuit board in a second module; eachrespective first printed circuit board module is connected to itscorresponding second printed circuit board module via one or more cable;the second printed circuit boards for all of the antennas are housedtogether in a location separate from the antenna rings; the plurality ofsecond printed circuit boards are arranged in a ring around the firstprinted circuit boards such that each respective second printed circuitboard is disposed adjacent its corresponding first printed circuitboard; the circuitry for each respective antenna controller includes ananalog to digital converter (ADC), carried on the one or more dedicatedprinted circuit board, such that the data representative of measuredcomplex electromagnetic field signals received by the correspondingantenna may be generated; the circuitry for each respective antennacontroller includes a digital signal processor carried on the one ormore dedicated printed circuit boards; the circuitry for each respectiveantenna controller utilizes a superheterodyne technology-basedarchitecture; the circuitry for each respective antenna controllerincludes a radio frequency (RF) transceiver stage that is connected tothe antenna, an intermediate frequency (IF) stage that is connected tothe RF transceiver stage, and a baseband (BB) data processing stage thatis connected to the intermediate frequency (IF) stage; the baseband (BB)data processing stage produces the data, representative of measuredelectromagnetic field signals received by the antenna, that is providedas output; the intermediate frequency (IF) stage utilizes quadraturemodulation to produce an IF signal that includes both in-phase andquadrature components; a common clock oscillator is provided to theintermediate frequency (IF) stage of each of the plurality of antennacontrollers; each intermediate frequency (IF) stage includes a frequencysynthesizer, utilizing the common clock oscillator as input, thatprovides a carrier signal of at least 100 MHz for an analogmodulation/demodulation process; the carrier signal provided by thefrequency synthesizer for the analog modulation/demodulation process,utilizing the common clock oscillator as input, is at least 1 GHz; theimaging chamber is cylindrical and includes at least three rings ofantennas; the imaging chamber includes at least five rings of antennas;the imaging chamber includes six rings of antennas; and/or each of theat least three rings of antennas includes a number of antennas that isequal to the number of antennas in each of the other rings.

In another feature of this aspect, the imaging chamber is semisphericaland includes at least three rings of antennas. In further features, theimaging chamber includes at least six rings of antennas; each of the atleast three rings of antennas includes a number of antennas that isdifferent from the number of antennas in each of the other rings.

In another feature of this aspect, the imaging chamber translatesrelative to the base; the imaging chamber translates horizontallyrelative to the base; the imaging chamber translates vertically relativeto the base; and/or the imaging chamber rotates upward and downwardrelative to the base.

In another feature of this aspect, the antennas are waveguide antennas.

In another feature of this aspect, the antennas are slot antennas.

Broadly defined, the present invention according to another aspect is anelectromagnetic tomographic scanner for use in imaging a human head,including: a base; an imaging chamber, supported on the base, thatdefines an imaging domain; at least one ring of antennas, supported bythe imaging chamber and encircling the imaging domain; and a pluralityof antenna controllers, each antenna controller comprising circuitry,utilizing a superheterodyne technology-based architecture, that isdedicated to a respective antenna in the ring of antennas; wherein thecircuitry of each respective antenna controller controls operation ofthe corresponding antenna and also provides, as output, datarepresentative of measured electromagnetic field signals received bysuch antenna.

Broadly defined, the present invention according to another aspect is anelectromagnetic tomographic scanner for use in imaging a human head,including: a base; an imaging chamber, supported on the base, thatdefines an imaging domain; at least one ring of antennas, supported bythe imaging chamber and encircling the imaging domain; a plurality ofantenna controllers, each antenna controller including radio frequency(RF) transmitter/receiver circuitry that is connected to an antenna ofan imaging chamber of an electromagnetic tomographic scanner, anintermediate frequency (IF) stage that is connected to the RFtransceiver transmitter/receiver circuitry, and a baseband (BB) dataprocessing stage that is connected to the intermediate frequency (IF)stage; wherein the baseband (BB) data processing stage produces, asoutput, data representative of measured electromagnetic field signalsreceived by the antenna.

In a feature of this aspect, the radio frequency (RF)transmitter/receiver circuitry, the intermediate frequency (IF) stage,and the baseband (BB) data processing stage for each respective antennacontroller are carried on a dedicated printed circuit board that isseparate from the respective printed circuit boards for the otherantenna controllers.

Broadly defined, the present invention according to another aspect is anantenna controller, in an electromagnetic tomographic scanner having animaging chamber, for an antenna arranged around the imaging chamber,including: radio frequency (RF) transmitter/receiver circuitry that isconnected to the antenna of the imaging chamber of the electromagnetictomographic scanner; an intermediate frequency (IF) stage that isconnected to the RF transceiver transmitter/receiver circuitry; and abaseband (BB) data processing stage that is connected to theintermediate frequency (IF) stage; wherein the baseband (BB) dataprocessing stage produces, as output, data representative of measuredelectromagnetic field signals received by the antenna.

In a feature of this aspect, the radio frequency (RF)transmitter/receiver circuitry, the intermediate frequency (IF) stage,and the baseband (BB) data processing stage for the antenna controllerare carried on a dedicated printed circuit board that is separate fromprinted circuit boards for other antenna controllers in theelectromagnetic tomographic scanner.

Broadly defined, the present invention according to another aspect is anelectromagnetic tomographic system for imaging a human head, including:a base; an imaging chamber, supported on the base, that defines animaging domain in which a human head is received; a plurality ofantennas, arranged in at least one ring, that are supported by theimaging chamber and encircle the imaging domain; a plurality of antennacontrollers, each dedicated to a respective antenna in the at least onering of antennas, wherein each antenna controller includes radiofrequency (RF) transceiver circuitry having a transmit side and areceive side that are alternately connected to the antenna using an RFswitch; and an image processing computer system communicativelyconnected to the antenna controllers; wherein while one of the antennasis transmitting an electromagnetic signal into the imaging domain, aplurality of the antennas in the at least one ring of antennas aresimultaneously receiving the electromagnetic signal after passingthrough the imaging domain; wherein, for each of the plurality ofantennas simultaneously receiving the electromagnetic signal afterpassing through the imaging domain, the corresponding antenna controllerfor the respective antenna is measuring the electromagnetic signalrespectively received at such antenna simultaneously with themeasurement of the electromagnetic signals received at the otherantennas of the plurality of antennas; wherein the respective antennacontroller dedicated to each antenna, of the plurality of antennassimultaneously receiving the electromagnetic signal after passingthrough the imaging domain, provides, as output, data representative ofmeasured electromagnetic field signals received by such antenna; andwherein the image processing computer system receives the datarepresentative of the measured electromagnetic field signals from theplurality of antenna controllers and images the human head from thereceived data.

In a feature of this aspect, the at least one ring of antennas includesa first ring of antennas and a second ring of antennas. In a furtherfeature, while one of the antennas in the first antenna ring istransmitting an electromagnetic signal into the imaging domain, aplurality of the antennas in both the first and second antenna rings aresimultaneously receiving the electromagnetic signal after passingthrough the imaging domain, and wherein, for each of the plurality ofantennas in both the first and second antenna rings that simultaneouslyreceive the electromagnetic signal after passing through the imagingdomain, the corresponding antenna controller for the respective antennais measuring the electromagnetic signal respectively received at suchantenna simultaneously with the measurement of the electromagneticsignals received at the other antennas of the plurality of antennas.

In another feature of this aspect, the circuitry of each antennacontroller, including the radio frequency (RF) transceiver circuitry, iscarried on a printed circuit board. In further features, the circuitryfor each respective antenna controller is carried on one or morededicated printed circuit board that are separate from the respectiveprinted circuit boards for the other antenna controllers; the systemfurther includes a plurality of antenna adapters, wherein each of theplurality of antenna adapters is dedicated to a respective antenna inthe ring of antennas, and wherein the antennas and antennas adaptersinclude circuitry that is carried on a dedicated printed circuit boardthat is separate from the respective printed circuit boards for theother antennas and antenna adapters; the circuitry for each antenna andantenna adapter and the circuitry for the corresponding antennacontroller are carried together on a single respective printed circuitboard; the circuitry for each antenna and antenna adapter is carried ona first printed circuit board in a first module and the circuitry forthe antenna controller corresponding to the antenna and antenna adapteris carried on a second printed circuit board in a second module; eachrespective first printed circuit board module is connected to itscorresponding second printed circuit board module via one or more cable;the second printed circuit boards for all of the antennas are housedtogether in a location separate from the at least one antenna ring; theplurality of second printed circuit boards are arranged in a ring aroundthe first printed circuit boards such that each respective secondprinted circuit board is disposed adjacent its corresponding firstprinted circuit board; the circuitry for each respective antennacontroller includes an analog to digital converter (ADC), carried on theone or more dedicated printed circuit board, such that the datarepresentative of measured complex electromagnetic field signalsreceived by the corresponding antenna may be generated; the circuitryfor each respective antenna controller includes a digital signalprocessor carried on the one or more dedicated printed circuit boards;the circuitry for each respective antenna controller utilizes asuperheterodyne technology-based architecture; the circuitry for eachrespective antenna controller includes, in additional to the radiofrequency (RF) transceiver circuitry, an intermediate frequency (IF)stage that is connected to the RF transceiver circuitry, and a baseband(BB) data processing stage that is connected to the intermediatefrequency (IF) stage; the baseband (BB) data processing stage producesthe data, representative of measured electromagnetic field signalsreceived by the antenna, that is provided as output; the intermediatefrequency (IF) stage utilizes quadrature modulation to produce an IFsignal that includes both in-phase and quadrature components; a commonclock oscillator is provided to the intermediate frequency (IF) stage ofeach of the plurality of antenna controllers; each intermediatefrequency (IF) stage includes a frequency synthesizer, utilizing thecommon clock oscillator as input, that provides a carrier signal of atleast 100 MHz for an analog modulation/demodulation process; and/or thecarrier signal provided by the frequency synthesizer for the analogmodulation/demodulation process, utilizing the common clock oscillatoras input, is at least 1 GHz.

In another feature of this aspect, the imaging chamber is cylindricaland includes at least three rings of antennas. In further features, theimaging chamber includes at least five rings of antennas; the imagingchamber includes six rings of antennas; each of the at least three ringsof antennas includes a number of antennas that is equal to the number ofantennas in each of the other rings.

In another feature of this aspect, the imaging chamber is semisphericaland includes at least three rings of antennas; the imaging chamberincludes at least six rings of antennas; and/or each of the at leastthree rings of antennas includes a number of antennas that is differentfrom the number of antennas in each of the other rings.

In another feature of this aspect, the imaging chamber translatesrelative to the base; the imaging chamber translates horizontallyrelative to the base; the imaging chamber translates vertically relativeto the base; the imaging chamber rotates upward and downward relative tothe base.

In another feature of this aspect, the antennas are waveguide antennas.

In another feature of this aspect, the antennas are slot antennas.

In another feature of this aspect, the image processing computer systemis integrated with the electromagnetic tomographic scanner.

In another feature of this aspect, the image processing computer systemis disposed in the same room as the electromagnetic tomographic scanner.

In another feature of this aspect, the image processing computer systemis disposed in a room that is different from a room in which theelectromagnetic tomographic scanner is disposed.

Broadly defined, the present invention according to another aspect is anelectromagnetic tomographic scanner for use in imaging a human head,including: a base; an imaging chamber, supported on the base, thatdefines an imaging domain in which a human head is received; a pluralityof antennas, arranged in at least one ring, that are supported by theimaging chamber and encircle the imaging domain; and a plurality ofantenna controllers, each dedicated to a respective antenna in the atleast one ring of antennas, wherein each antenna controller includesradio frequency (RF) transceiver circuitry having a transmit side and areceive side that are alternately connected to the antenna using an RFswitch; wherein while one of the antennas is transmitting anelectromagnetic signal into the imaging domain, a plurality of theantennas in the at least one ring of antennas are simultaneouslyreceiving the electromagnetic signal after passing through the imagingdomain; wherein, for each of the plurality of antennas simultaneouslyreceiving the electromagnetic signal after passing through the imagingdomain, the corresponding antenna controller for the respective antennais measuring the electromagnetic signal respectively received at suchantenna simultaneously with the measurement of the electromagneticsignals received at the other antennas of the plurality of antennas; andwherein the respective antenna controller dedicated to each antenna, ofthe plurality of antennas simultaneously receiving the electromagneticsignal after passing through the imaging domain, provides, as output,data representative of measured electromagnetic field signals receivedby such antenna.

In a feature of this aspect, the at least one ring of antennas includesa first ring of antennas and a second ring of antennas. In a furtherfeature, while one of the antennas in the first antenna ring istransmitting an electromagnetic signal into the imaging domain, aplurality of the antennas in both the first and second antenna rings aresimultaneously receiving the electromagnetic signal after passingthrough the imaging domain, and wherein, for each of the plurality ofantennas in both the first and second antenna rings that simultaneouslyreceive the electromagnetic signal after passing through the imagingdomain, the corresponding antenna controller for the respective antennais measuring the electromagnetic signal respectively received at suchantenna simultaneously with the measurement of the electromagneticsignals received at the other antennas of the plurality of antennas.

In another feature of this aspect, the circuitry of each antennacontroller, including the radio frequency (RF) transceiver circuitry, iscarried on a printed circuit board. In further features, the circuitryfor each respective antenna controller is carried on one or morededicated printed circuit board that are separate from the respectiveprinted circuit boards for the other antenna controllers; the scannerfurther includes a plurality of antenna adapters, wherein each of theplurality of antenna adapters is dedicated to a respective antenna inthe ring of antennas, and wherein the antennas and antennas adaptersinclude circuitry that is carried on a dedicated printed circuit boardthat is separate from the respective printed circuit boards for theother antennas and antenna adapters; the circuitry for each antenna andantenna adapter and the circuitry for the corresponding antennacontroller are carried together on a single respective printed circuitboard; the circuitry for each antenna and antenna adapter is carried ona first printed circuit board in a first module and the circuitry forthe antenna controller corresponding to the antenna and antenna adapteris carried on a second printed circuit board in a second module; eachrespective first printed circuit board module is connected to itscorresponding second printed circuit board module via one or more cable;the second printed circuit boards for all of the antennas are housedtogether in a location separate from the at least one antenna ring; theplurality of second printed circuit boards are arranged in a ring aroundthe first printed circuit boards such that each respective secondprinted circuit board is disposed adjacent its corresponding firstprinted circuit board; the circuitry for each respective antennacontroller includes an analog to digital converter (ADC), carried on theone or more dedicated printed circuit board, such that the datarepresentative of measured complex electromagnetic field signalsreceived by the corresponding antenna may be generated; the circuitryfor each respective antenna controller includes a digital signalprocessor carried on the one or more dedicated printed circuit boards;the circuitry for each respective antenna controller utilizes asuperheterodyne technology-based architecture; the circuitry for eachrespective antenna controller includes, in additional to the radiofrequency (RF) transceiver circuitry, an intermediate frequency (IF)stage that is connected to the RF transceiver circuitry, and a baseband(BB) data processing stage that is connected to the intermediatefrequency (IF) stage; the baseband (BB) data processing stage producesthe data, representative of measured electromagnetic field signalsreceived by the antenna, that is provided as output; the intermediatefrequency (IF) stage utilizes quadrature modulation to produce an IFsignal that includes both in-phase and quadrature components; a commonclock oscillator is provided to the intermediate frequency (IF) stage ofeach of the plurality of antenna controllers; each intermediatefrequency (IF) stage includes a frequency synthesizer, utilizing thecommon clock oscillator as input, that provides a carrier signal of atleast 100 MHz for an analog modulation/demodulation process; and/or thecarrier signal provided by the frequency synthesizer for the analogmodulation/demodulation process, utilizing the common clock oscillatoras input, is at least 1 GHz.

In another feature of this aspect, the imaging chamber is cylindricaland includes at least three rings of antennas. In further features, theimaging chamber includes at least five rings of antennas; the imagingchamber includes six rings of antennas; and/or each of the at leastthree rings of antennas includes a number of antennas that is equal tothe number of antennas in each of the other rings.

In another feature of this aspect, the imaging chamber is semisphericaland includes at least three rings of antennas. In further features, theimaging chamber includes at least six rings of antennas; and/or each ofthe at least three rings of antennas includes a number of antennas thatis different from the number of antennas in each of the other rings.

In another feature of this aspect, the imaging chamber translatesrelative to the base. In further features, the imaging chambertranslates horizontally relative to the base; the imaging chambertranslates vertically relative to the base; and/or the imaging chamberrotates upward and downward relative to the base.

In another feature of this aspect, the antennas are waveguide antennas.

In another feature of this aspect, the antennas are slot antennas.

Broadly defined, the present invention according to another aspect is amethod of conducting electromagnetic tomography for imaging a humanhead, including: positioning a human head through an opening in an endof an imaging chamber of an electromagnetic tomographic scanner, whereinthe imaging chamber defines an imaging domain such that at least aportion of the brain is in the imaging domain, wherein the imagingchamber supports at least one ring of antennas that encircles theimaging domain, and wherein each antenna has a dedicated antennacontroller that includes radio frequency (RF) transceiver circuitryhaving a transmit side and a receive side that are alternately connectedto the antenna using an RF switch; controlling one antenna, via theantenna's corresponding antenna controller, to transmit anelectromagnetic signal into the imaging domain; controlling a pluralityof the antennas, via each respective antenna's antenna controller, toreceive the electromagnetic signal after passing through the imagingdomain such that all of the antennas of the plurality of antennas arereceiving the electromagnetic signals simultaneously; for each of theplurality of receiving antennas, measuring the respective receivedelectromagnetic signal such that all of the simultaneously receivedelectromagnetic signals are measured simultaneously; for each of theplurality of receiving antennas, outputting data representative of themeasured electromagnetic field signals received by such antenna;receiving the data at an image processing computer; and carrying out anelectromagnetic tomography image reconstruction process at the imageprocessing center to produce an image of the brain.

In a feature of this aspect, the at least one ring of antennas includesa first ring of antennas and a second ring of antennas. In a furtherfeature, the step of controlling a plurality of the antennas, via eachrespective antenna's antenna controller, to receive the electromagneticsignal after passing through the imaging domain includes controlling aplurality of the antennas in both the first and second antenna rings,via each respective antenna's antenna controller, to receive theelectromagnetic signal after passing through the imaging domain suchthat all of the antennas of the plurality of antennas are receiving theelectromagnetic signals simultaneously.

In another feature of this aspect, the circuitry of each antennacontroller, including the radio frequency (RF) transceiver circuitry, iscarried on a printed circuit board. In further features, the circuitryfor each respective antenna controller is carried on one or morededicated printed circuit board that are separate from the respectiveprinted circuit boards for the other antenna controllers; the methodfurther includes a plurality of antenna adapters, wherein each of theplurality of antenna adapters is dedicated to a respective antenna inthe ring of antennas, and wherein the antennas and antennas adaptersinclude circuitry that is carried on a dedicated printed circuit boardthat is separate from the respective printed circuit boards for theother antennas and antenna adapters; the circuitry for each antenna andantenna adapter and the circuitry for the corresponding antennacontroller are carried together on a single respective printed circuitboard; the circuitry for each antenna and antenna adapter is carried ona first printed circuit board in a first module and the circuitry forthe antenna controller corresponding to the antenna and antenna adapteris carried on a second printed circuit board in a second module; eachrespective first printed circuit board module is connected to itscorresponding second printed circuit board module via one or more cable;the second printed circuit boards for all of the antennas are housedtogether in a location separate from the at least one antenna ring; theplurality of second printed circuit boards are arranged in a ring aroundthe first printed circuit boards such that each respective secondprinted circuit board is disposed adjacent its corresponding firstprinted circuit board; the circuitry for each respective antennacontroller includes an analog to digital converter (ADC), carried on theone or more dedicated printed circuit board, such that the datarepresentative of measured complex electromagnetic field signalsreceived by the corresponding antenna may be generated; the circuitryfor each respective antenna controller includes a digital signalprocessor carried on the one or more dedicated printed circuit boards;the circuitry for each respective antenna controller utilizes asuperheterodyne technology-based architecture; the circuitry for eachrespective antenna controller includes, in additional to the radiofrequency (RF) transceiver circuitry, an intermediate frequency (IF)stage that is connected to the RF transceiver circuitry, and a baseband(BB) data processing stage that is connected to the intermediatefrequency (IF) stage; the method further includes a step of producing,via the baseband (BB) data processing stage produces, the data,representative of measured electromagnetic field signals received by theantenna, that is provided as output; the method further includes a stepof utilizing quadrature modulation, by the intermediate frequency (IF)stage, to produce an IF signal that includes both in-phase andquadrature components; the method further includes a step of providing acommon clock oscillator to the intermediate frequency (IF) stage of eachof the plurality of antenna controllers; each intermediate frequency(IF) stage includes a frequency synthesizer, utilizing the common clockoscillator as input, that provides a carrier signal of at least 100 MHzfor an analog modulation/demodulation process; and/or the carrier signalprovided by the frequency synthesizer for the analogmodulation/demodulation process, utilizing the common clock oscillatoras input, is at least 1 GHz.

In another feature of this aspect, the imaging chamber is cylindricaland includes at least three rings of antennas; the imaging chamberincludes at least five rings of antennas; the imaging chamber includessix rings of antennas; and/or each of the at least three rings ofantennas includes a number of antennas that is equal to the number ofantennas in each of the other rings.

In another feature of this aspect, the imaging chamber is semisphericaland includes at least three rings of antennas. In further features, theimaging chamber includes at least six rings of antennas; and/or each ofthe at least three rings of antennas includes a number of antennas thatis different from the number of antennas in each of the other rings.

In another feature of this aspect, the imaging chamber translatesrelative to the base. In further features, the method further includes astep of translating the imaging chamber horizontally, relative to thebase, to position the imaging chamber relative to the human head; themethod further includes a step of translating the imaging chambervertically, relative to the base, to position the imaging chamberrelative to the human head; and/or the method further includes a step ofrotating upward and downward, relative to the base, to position theimaging chamber relative to the human head.

In another feature of this aspect, the antennas are waveguide antennas.

In another feature of this aspect, the antennas are slot antennas.

In another feature of this aspect, the image processing computer systemis integrated with the electromagnetic tomographic scanner.

In another feature of this aspect, the image processing computer systemis disposed in the same room as the electromagnetic tomographic scanner.

In another feature of this aspect, the image processing computer systemis disposed in a room that is different from a room in which theelectromagnetic tomographic scanner is disposed.

Broadly defined, the present invention according to another aspect is anelectromagnetic tomographic scanner for use in imaging a live human bodypart, including: an imaging chamber, supported on a base, that definesan imaging domain in which at least a portion of a live human body partis received, wherein the imaging chamber has an open end that may becovered by a lid; a plurality of antennas, arranged in at least onering, that are supported by the imaging chamber and encircle the imagingdomain, wherein the antennas are controllable to receive a transmittedelectromagnetic signal after passing through the imaging domain; acontroller for controlling one or more of the plurality of antennas; alid that is attachable to the open end of the imaging chamber, whereinthe lid includes a hollow boundary model that mimics the anatomy of aportion of the human, extending away from the imaging domain of theimaging chamber, and wherein the portion of the human whose anatomy ismimicked is the portion of the human that is expected to be disposedoutside of the imaging domain when the portion of the live human bodypart is received in the imaging domain; and a quantity of a matchingmedia, the matching media filling an interior of the hollow boundarymodel while an empty field measurement is carried out via the at leastone ring of antennas.

In a feature of this aspect, the hollow boundary model mimics theanatomy of a portion of the head of the human. In further features, thehollow boundary model mimics the anatomy of a lower portion of the humanhead; the lid includes a frame having a central opening that issurrounded by the hollow boundary model such that when the lid isattached to the open end of the imaging chamber, the interior of thehollow boundary model is in fluid communication with the imaging domain;the central opening is ellipsoidal; the frame is rigid; the lid is afull lid and wherein the hollow boundary model defines a separateinterior cavity, not in fluid communication with the imaging domain,that is filled by the matching media; the matching media is a liquid;the lid is temporarily sealed to the open end of the imaging chamberwhile the empty field measurement is carried out; the matching media isa liquid, and wherein the temporary seal between the lid and the openend of the imaging chamber prevents leakage of the matching media frombetween the imaging chamber and the lid; the matching media is a gel;the lid is attached, but not necessarily sealed, to the open end of theimaging chamber while the empty field measurement is carried out, andwherein the consistency of the gel prevents leakage from between theimaging chamber and the lid; the imaging chamber is at least partiallytilted, while the empty field measurement is carried out, such thatmatching media is caused to flow into the interior of the hollowboundary model; and/or the imaging chamber is adjustable during use froma vertical orientation, wherein the open end of the imaging chamberfaces upward, to a horizontal orientation, wherein the open end of theimaging chamber faces sideward.

Broadly defined, the present invention according to another aspect is amethod of conducting electromagnetic tomography for imaging a humanhead, including: providing an imaging chamber, supported on a base, thatdefines an imaging domain in which at least a portion of a live humanbody part may be received, wherein the imaging chamber has an open end,wherein the imaging chamber supports a plurality of antennas, arrangedin at least one ring, that encircle the imaging domain, and wherein eachantenna may be controlled by a controller; temporarily attaching a lidto the open end of the imaging chamber, wherein the lid includes ahollow boundary model that mimics the anatomy of a portion of the human,extending away from the imaging domain of the imaging chamber, andwherein the portion of the human whose anatomy is mimicked is theportion of the human that is expected to be disposed outside of theimaging domain when the human's head is received in the imaging domain;filling an interior of the hollow boundary model with a matching media;without the human in the imaging domain, carrying out a process of emptyfield measurement by transmitting electromagnetic signals and receivingthem, after passing through the imaging domain, at each of a pluralityof the antennas in the at least one ring; with the lid in a removedstate, positioning at least a portion of a live human body part throughthe opening in the end of the imaging chamber, and, subsequently,carrying out a process of full field measurement by transmittingelectromagnetic signals and receiving them, after passing through theimaging domain, at each of a plurality of the antennas in the at leastone ring; and carrying out an electromagnetic tomography imagereconstruction process using both the empty field measurements and thefull field measurements.

In a feature of this aspect, the hollow boundary model mimics theanatomy of a portion of the head of the human. In further features, themethod further includes a step of filling the imaging domain of theimaging chamber with a further quantity of the matching media, andwherein the imaging domain of the imaging chamber contains the matchingmedia during both the empty field measurement process and the full fieldmeasurement process; the hollow boundary model is a closed cavity thatis not in fluid communication with the imaging domain of the imagingchamber; the hollow boundary model is open such that the interior of thehollow boundary model is in fluid communication with the imaging domainof the imaging chamber when the lid is temporarily attached to the openend of the imaging chamber; the hollow boundary model mimics the anatomyof a lower portion of the human head; the lid includes a frame having acentral opening that is surrounded by the hollow boundary model, andwherein the step of temporarily attaching a lid to the open end of theimaging chamber includes attaching the lid such that the interior of thehollow boundary model is in fluid communication with the imaging domain;the central opening is ellipsoidal; the frame is rigid; the lid is afull lid, wherein the hollow boundary model defines a separate interiorcavity, wherein filling an interior of the hollow boundary model with amatching media includes filling the separate interior cavity with amatching media, and wherein the step of temporarily attaching a lid tothe open end of the imaging chamber includes attaching the lid such thatthe separate interior cavity of the hollow boundary model is not influid communication with the imaging domain; the matching media is aliquid; the step of temporarily attaching a lid to the open end of theimaging chamber includes temporarily sealing the lid to the open end ofthe imaging chamber, and wherein the step of carrying out a process ofempty field measurement is carried out while the lid is temporarilysealed to the open end of the imaging chamber; the matching media is aliquid, and wherein the temporary seal between the lid and the open endof the imaging chamber prevents leakage of the matching media frombetween the imaging chamber and the lid; the matching media is a gel;the lid is attached, but not necessarily sealed, to the open end of theimaging chamber while the empty field measurement is carried out, andwherein the consistency of the gel prevents leakage from between theimaging chamber and the lid; the method further includes a step oftilting the imaging chamber such that matching media is caused to flowinto the interior of the hollow boundary model, and wherein the step ofcarrying out a process of empty field measurement is carried out whilethe imaging chamber is at least partially tilted; and/or the methodfurther includes a step of adjusting the imaging chamber, during use,from a vertical orientation, wherein the open end of the imaging chamberfaces upward, to a horizontal orientation, wherein the open end of theimaging chamber faces sideward.

Broadly defined, the present invention according to another aspect is amethod of conducting electromagnetic tomography for imaging a humanhead, including: providing an imaging chamber, supported on a base, thatdefines an imaging domain in which at least a portion of a human headmay be received, wherein the imaging chamber has an open end, whereinthe imaging chamber supports at least one ring of antennas thatencircles the imaging domain, and wherein each antenna may be controlledby a controller; without the human in the imaging domain, carrying out aprocess of empty field measurement by transmitting electromagneticsignals from respective antennas and receiving them, after passingthrough the imaging domain, at each of a plurality of the antennas inthe at least one ring; storing the empty field measurements; producing afirst tensor, represented by S_(i,j) ^(meas,empty), corresponding to themeasured empty field for each pair of transmitting and receivingantennas i,j; positioning a human head through the opening in the end ofthe imaging chamber; with the head of the human positioned through theopen end of the imaging chamber such that at least a portion of thehuman's brain is disposed in the imaging domain, carrying out a processof full field measurement by transmitting electromagnetic signals fromrespective antennas and receiving them, after passing through theimaging domain, at each of a plurality of the antennas in the at leastone ring, wherein the measurements; producing a second tensor,represented by S_(i,j) ^(meas,full), corresponding to the measured fullfield for each pair of transmitting and receiving antennas i,j;producing a third tensor, represented by S_(i,j) ^(meas,sct),corresponding to the scattering caused by the human's head, via thealgebraic subtraction S_(i,j,k) ^(meas,sct)=S_(i,j,k)^(meas,full)−S_(i,j,k) ^(meas,empty); using at least the first, second,and third tensors, carrying out an iterative process involving thesolving of a direct problem, the solving of an inverse problem, thecalculation of updated dielectric permittivity values corresponding tothe human's brain in the imaging domain, and the computation of afunctional that is evaluated for convergence to predetermined criteria,wherein an antenna-by-antenna normalization is utilized in thefunctional such that S_(ij)=s_(ij) ^(sct)/s_(ij) ^(empty); and whenconvergence is achieved, producing a reconstructed image of a portion ofthe human's brain by plotting a final dielectric permittivitydistribution.

In a feature of this aspect, the method further includes a step offormulating a matching media to have a dielectric permittivity of(ϵ=ϵ′+jϵ″) such that ϵ′ is in the range of about 40 to 45 and ϵ″ is inthe range of about 17 to 21, wherein the electromagnetic tomographysystem includes an electromagnetic tomographic scanner and an imageprocessing computer system, and wherein the electromagnetic tomographicscanner includes an imaging chamber, supported on a base, that includesan open end and that defines an imaging domain; the method furthercomprises at least partially filling the imaging chamber with thematching media; and the step of carrying out a process of full fieldmeasurement with the head of the human positioned through the open endof the imaging chamber is executed with the imaging chamber at leastpartially filled with the matching media. In further features, the stepof formulating a matching media includes formulating a matching mediathat is a fluid; the step of formulating a matching media includesformulating a matching media that is a gel; the step of formulating amatching media includes formulating a matching media that includesglycerol and water; the step of formulating a matching media includesformulating a matching media that further includes brine; the step offormulating a matching media includes formulating a matching media thatincludes brine and water; the method further includes steps of, first,rotating the imaging chamber, relative to the base, until the open endof the imaging chamber is oriented to face upward so as to receive andretain the matching media; and then, rotating the imaging chamber,relative to the base, until the open end of the imaging chamber isoriented to face sideways so as to receive the human head, while thehead is horizontally oriented, and remains in the sideways orientationduring the step of conducting the full field measurement; the methodfurther includes a step of carrying out a calibration process for thesystem while the imaging chamber is oriented to face upward so as toretain the matching media; the calibration process includes use of anequalization technique to adjust for variations between receivers of theplurality of receivers; the calibration process includes temporarilypositioning a reference antenna in the imaging chamber and conductingelectromagnetic field measurements via the reference antenna; and/or themethod further includes a step of measuring the empty field in theimaging domain is measured while the imaging chamber is oriented to faceupward so as to retain the matching media.

Further areas of applicability of the present invention will becomeapparent from the detailed description provided hereinafter. It shouldbe understood that the detailed description and specific examples, whileindicating the preferred embodiment of the invention, are intended forpurposes of illustration only and are not intended to limit the scope ofthe invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The patent or application file contains at least one drawing executed incolor. Copies of this patent or patent application publication withcolor drawing(s) will be provided by the Office upon request and paymentof the necessary fee.

Further features, embodiments, and advantages of the present inventionwill become apparent from the following detailed description withreference to the drawings, wherein:

FIG. 1 is a simplified schematic illustration of portions of anelectromagnetic tomography (EMT) system;

FIG. 2 is a block diagram of an electromagnetic tomography (EMT) systemin accordance with one or more preferred embodiments of the presentinvention;

FIG. 3 is a side view of the electromagnetic tomographic scanner of FIG.2;

FIG. 4A is a perspective view of the electromagnetic tomographic scannerfor head imaging of FIG. 3;

FIG. 4B is a perspective view of the scanner of FIG. 4A shown with thehead positioned in the imaging domain of the imaging chamber inpreparation for imaging;

FIG. 5 is a perspective view of a first alternative electromagnetictomographic scanner for use in the EMT system of FIG. 2;

FIGS. 6A and 6B are side views of a second alternative electromagnetictomographic scanner for use in the EMT system of FIG. 2;

FIG. 7 is a side view of a third alternative electromagnetic tomographicscanner for use in the EMT system of FIG. 2;

FIGS. 8A and 8B are side views of a cylindrical electromagnetictomography (EMT) imaging chamber, shown without and with antennasinstalled therein, for use in the imaging chamber system in accordancewith one or more preferred embodiments of the present invention;

FIG. 9 is a side cross-sectional view of an exemplary cylindricalelectromagnetic tomography (EMT) imaging chamber for use in anelectromagnetic tomographic scanner in accordance with one or morepreferred embodiments of the present invention;

FIGS. 10A and 10B are side views of an alternative sphericalelectromagnetic tomography (EMT) imaging chamber, shown without and withantennas installed therein, for use in an imaging chamber system inaccordance with one or more preferred embodiments of the presentinvention;

FIG. 11 is a graphical representation of a preferred radiation patternfor use in one or more preferred embodiments of the present invention;

FIG. 12 is a simplified block diagram of hardware for simultaneousantenna operation in an EMT imaging chamber;

FIG. 13 is a simplified block diagram of hardware for sequential antennaoperation in an EMT imaging chamber;

FIG. 14 is a block diagram illustrating the application of asuperheterodyne architecture for use in the electromagnetic tomographicscanner;

FIG. 15 is a block diagram illustrating the application of asynchronized superheterodyne architecture for use in the electromagnetictomographic scanner;

FIG. 16 is a flow diagram of an exemplary calibration process for use inone or more preferred embodiments of the EMT system shown in FIG. 3;

FIG. 17 is a side view of the moveable imaging chamber system of FIG. 3,shown in a vertical position;

FIG. 18A is a schematic diagram of a reference antenna temporarilypositioned in the center of an imaging chamber;

FIG. 18B is a schematic diagram of the reference antenna and imagingchamber of FIG. 18A, illustrating an omnidirectional radiation patternof the antenna;

FIG. 18C is a schematic diagram of one antenna of interest transmittingfor purposes of measuring data received at the reference antenna;

FIG. 19 is an exemplary graphical representation of measured signalsreceived from the reference antenna by various antennas around a ring;

FIG. 20A is a perspective view of a lid, including a frame supporting ahollow boundary model, for use in at least some embodiments in mimickingthe part of the body outside of the imaging chamber during empty fieldmeasurements;

FIG. 20B is a front view of the frame of FIG. 20A;

FIG. 20C is a side view of the electromagnetic tomographic scanner ofFIG. 3, shown with the lid of FIG. 20A installed thereon;

FIG. 21 is a side cross-sectional view of the exemplary cylindrical EMTimaging chamber of FIG. 9;

FIGS. 22A and 22B are graphical representations of the result of 2Dimage reconstruction for the human head phantom inside the chamber ofFIG. 21 using the empty field measurement taken with a full lid;

FIG. 22C is a graphical representation of the result of 2D imagereconstruction for the same human head phantom of FIGS. 22A and 22Busing the output from the first antenna ring, but where the empty fieldmeasurement was carried out with the partial lid and hollow boundarymodel of FIG. 20A covering the imaging chamber;

FIG. 23 is a high-level flow diagram of a 3D electromagnetic tomographyimage reconstruction (EMTIR) method for use in an EMT system inaccordance with one or more preferred embodiments of the presentinvention;

FIG. 24 is a graphical representation (rendered in a black-and-whiteversion and a color version) of an image reconstruction, for an object,using opposite-antenna normalization; and

FIG. 25 is a graphical representation (rendered in a black-and-whiteversion and a color version) of an image reconstruction, for the sameobject as that of FIG. 24 but using antenna-by-antenna normalization atearly iterations.

DETAILED DESCRIPTION

As a preliminary matter, it will readily be understood by one havingordinary skill in the relevant art (“Ordinary Artisan”) that the presentinvention has broad utility and application. Furthermore, any embodimentdiscussed and identified as being “preferred” is considered to be partof a best mode contemplated for carrying out the present invention.Other embodiments also may be discussed for additional illustrativepurposes in providing a full and enabling disclosure of the presentinvention. As should be understood, any embodiment may incorporate onlyone or a plurality of the above-disclosed aspects of the invention andmay further incorporate only one or a plurality of the above-disclosedfeatures. Moreover, many embodiments, such as adaptations, variations,modifications, and equivalent arrangements, will be implicitly disclosedby the embodiments described herein and fall within the scope of thepresent invention.

Accordingly, while the present invention is described herein in detailin relation to one or more embodiments, it is to be understood that thisdisclosure is illustrative and exemplary of the present invention, andis made merely for the purposes of providing a full and enablingdisclosure of the present invention. The detailed disclosure herein ofone or more embodiments is not intended, nor is to be construed, tolimit the scope of patent protection afforded the present invention,which scope is to be defined by the claims and the equivalents thereof.It is not intended that the scope of patent protection afforded thepresent invention be defined by reading into any claim a limitationfound herein that does not explicitly appear in the claim itself.

Thus, for example, any sequence(s) and/or temporal order of steps ofvarious processes or methods that are described herein are illustrativeand not restrictive. Accordingly, it should be understood that, althoughsteps of various processes or methods may be shown and described asbeing in a sequence or temporal order, the steps of any such processesor methods are not limited to being carried out in any particularsequence or order, absent an indication otherwise. Indeed, the steps insuch processes or methods generally may be carried out in variousdifferent sequences and orders while still falling within the scope ofthe present invention. Accordingly, it is intended that the scope ofpatent protection afforded the present invention is to be defined by theappended claims rather than the description set forth herein.

Additionally, it is important to note that each term used herein refersto that which the Ordinary Artisan would understand such term to meanbased on the contextual use of such term herein. To the extent that themeaning of a term used herein—as understood by the Ordinary Artisanbased on the contextual use of such term—differs in any way from anyparticular dictionary definition of such term, it is intended that themeaning of the term as understood by the Ordinary Artisan shouldprevail.

Regarding applicability of 35 U.S.C. § 112, ¶6, no claim element isintended to be read in accordance with this statutory provision unlessthe explicit phrase “means for” or “step for” is actually used in suchclaim element, whereupon this statutory provision is intended to applyin the interpretation of such claim element.

Furthermore, it is important to note that, as used herein, “a” and “an”each generally denotes “at least one,” but does not exclude a pluralityunless the contextual use dictates otherwise. Thus, reference to “apicnic basket having an apple” describes “a picnic basket having atleast one apple” as well as “a picnic basket having apples.” Incontrast, reference to “a picnic basket having a single apple” describes“a picnic basket having only one apple.”

When used herein to join a list of items, “or” denotes “at least one ofthe items,” but does not exclude a plurality of items of the list. Thus,reference to “a picnic basket having cheese or crackers” describes “apicnic basket having cheese without crackers,” “a picnic basket havingcrackers without cheese,” and “a picnic basket having both cheese andcrackers.” Finally, when used herein to join a list of items, “and”denotes “all of the items of the list.” Thus, reference to “a picnicbasket having cheese and crackers” describes “a picnic basket havingcheese, wherein the picnic basket further has crackers,” as well asdescribes “a picnic basket having crackers, wherein the picnic basketfurther has cheese.”

Referring now to the drawings, in which like numerals represent likecomponents throughout the several views, one or more preferredembodiments of the present invention are next described. The followingdescription of one or more preferred embodiment(s) is merely exemplaryin nature and is in no way intended to limit the invention, itsapplication, or uses.

FIG. 2 is a block diagram of an electromagnetic tomography (EMT) system100 in accordance with one or more preferred embodiments of the presentinvention. As shown therein, the EMT system 100 includes anelectromagnetic tomographic scanner 110, a local initial imagevalidation computer 129 which might be integrated within the system orstand-alone, and a remote image processing computer system 128. Thelocal computer 129, which in at least some embodiments is located in thesame room as the electromagnetic tomographic scanner 110 or integratedwithin the scanner 110, may be connected to the electromagnetictomographic scanner 110 via wired connection or wirelessly. In variousembodiments, the remote image processing computer system 128 is locatedelsewhere in the same facility (e.g., same hospital) as theelectromagnetic tomographic scanner 110, at the (external) premises ofthe electromagnetic tomographic scanner supplier, at the (external)premises of a third party Image Processing Center (IPC), or otherlocation.

FIG. 3 is a side view of the electromagnetic tomographic scanner 110 ofFIG. 2. As shown therein, the electromagnetic tomographic scanner 110 islocated at the end of a bed 120 on which a human patient 108 is lying.The scanner 110 includes a base 140, which in at least some embodimentsmay be rolled from one location to another, and an imaging chambersystem 150, including an imaging chamber 160 defining an imaging domain21. The imaging chamber 160 is preferably provided with a padded opening161 that may, for example, be manufactured from a soft foam with asmooth surface. The imaging chamber 160 is capable of translatingrelative to the base in at least one direction, angle, or the like.Preferably, the imaging chamber 160 is capable of moving horizontally,toward and away from the top of the patient's head 109, a distance of upto 30-40 cm. The patient 108, the bed 120, and/or the scanner 110 aremaneuvered such that the patient's head 109 is positioned in the imagingchamber 160.

FIG. 4A is a perspective view of the electromagnetic tomographic scanner110 for head imaging of FIG. 3, and FIG. 4B is a perspective view of thescanner 110 of FIG. 4A shown with the head 109 positioned in the imagingdomain 21 of the imaging chamber 160 in preparation for imaging. In atleast some embodiments, the computer system 128 and its data processingfunctionality and imaging software is directly connected to the scanner110, while in other embodiments some or all of the computer system 128is remotely connected through wireless technology and/or high speed wireconnections. Functionally, much of the operation of the EMT system 100may be similar to that described in the aforementioned U.S. Pat. No.9,414,749 but various particular embodiments and features may bedescribed herein.

It will be appreciated that in various embodiments, the electromagnetictomographic scanner may take various forms. In this regard, FIG. 5 is aperspective view of a first alternative electromagnetic tomographicscanner 410 for use in the EMT system 100 of FIG. 2, and FIGS. 6A and 6Bare side views of a second alternative electromagnetic tomographicscanner 510 for use in the EMT system 100 of FIG. 2. In the scanner 410of FIG. 5, an imaging chamber 460, having a padded opening 461, isdisposed at the upper end of an arm 445 that rotates with respect to awheel-mounted base 440 about a horizontal axis. This scanner 410 may berolled from the side into position at the head of a bed 120, and theimaging chamber 460 may be rotated downward to match the orientation ofa patient 108 who is propped up in the bed 120 such that his head 109 isoriented at an angle of approximately 30 degrees (although other anglesare likewise possible). In the scanner 510 of FIGS. 6A and 6B, animaging chamber 560, having a padded opening 561, is arranged totranslate horizontally a distance of up to 15-20 cm relative to acarriage 545 that itself can be translated vertically on a wheel-mountedbase 540. This scanner 510 may be rolled into position at the head of abed 120, and the imaging chamber 560 may be adjusted vertically andhorizontally to match the position of a patient 108 who is lyinggenerally flat on the bed 120 such that his head 109 is positioned nearthe head of the bed 120.

In yet further embodiments, a bed may be incorporated into anelectromagnetic tomographic scanner. In this regard, FIG. 7 is a sideview of a third alternative electromagnetic tomographic scanner 610 foruse in the EMT system 100 of FIG. 2. In this scanner 610, an imagingchamber system 650, including an imaging chamber 660 having a paddedopening 661, is carried by an integrated bed 620. The imaging chamber660 preferably translates horizontally a distance of up to 30-40 cmtoward and away from the head 109 of the patient 108.

Although the various electromagnetic tomographic scanners describedherein 110,410,510,610 take different forms from one another, eachscanner provides the ability to position a base, which is generally butnot necessarily always supported on wheels, near a patient 108,supported on a bed, and then repositioning a movable portion, includingan imaging chamber, relative to the patient's head such that itsurrounds the portion of the patient's head 109 to be imaged without thepatient 108 being required to move. Furthermore, the movable portion ofthe scanner includes not only the imaging chamber but the electronics,as described further herein, such that the electronics move with theimaging chamber relative to the base. The movement may be linear(vertical, horizontal, or in some cases at a non-vertical/non-horizontalangle), radial, or both. In some embodiments, movement is preferablyeffectuated manually, so as to provide more immediate control by anoperator, but in at least some embodiments some measure of automatedcontrol (such as may be applied via a foot pedal) may be provided. In atleast some embodiments, the location and/or orientation of the imagingchamber may be locked into place once positioned as desired. Suchscanners may be physically located in hospital environments (e.g.,emergency department, intensive care units (ICUs), specialized strokeunits, or the like) or, in some embodiments, in other locations (e.g, anambulance). It will be appreciated that a single hospital or otherfacility may make use of multiple scanners, and that such scanners mayor may not be of different types, but that a plurality of scanners maybe supported by a single image processing computer system 128 that istypically located remotely from some or all of the scanners. For thesake of simplicity, however, only a single scanner 110 of the type shownin FIG. 3 is generally referenced in the following description.

As described above, EMT imaging of high dielectric contrast objects,including biological objects, involves the very complicated problem ofso-called “diffraction tomography.” A high dielectric contrast betweentissues with high water content, such as but not limited to muscletissue, and low water content, such as but not limited to bone, presentsan additional complication when using EM fields for imaging. Specializedhardware in the scanner 110 and image reconstruction methods 3100 arepreferably utilized to solve the so-called “diffraction tomography”problem.

As noted previously, the imaging domain 21 of the imaging chamber system150 is defined by and within the imaging chamber 160. In this regard,FIGS. 8A and 8B are side views of a cylindrical electromagnetictomography (EMT) imaging chamber 160, shown without and with antennas165 installed therein, for use in the imaging chamber system 150 inaccordance with one or more preferred embodiments of the presentinvention. In the illustrated embodiment, the antennas 165 are slotantennas, but it will be appreciated that other types of antennas, suchas waveguide antennas, may be used instead. In the illustratedembodiment, the cylindrical imaging chamber 160 includes 192 antennas165, each with an adaptor, that are arranged in six rings of 32 antennaseach. In some embodiments, the antenna adaptors are linked to a box of192 specifically designed printed circuit boards (PCBs) by semi-rigidcoaxial cables, or are integrated directly into PCBs, wherein the PCBsprovide control and data processing functionality, including thegeneration of the electromagnetic (EM) signals to be transmitted fromthe emitting antennas and the measurement of complex EM signals in thereceiving antennas. However, in some embodiments, other physicalimplementations are possible; for example, as described below, thenumber of separate control devices may be reduced through the use ofsequential, rather than simultaneous, operation of the antennas.

FIG. 9 is a side cross-sectional view of an exemplary cylindricalelectromagnetic tomography (EMT) imaging chamber 860 for use in anelectromagnetic tomographic scanner in accordance with one or morepreferred embodiments of the present invention. As shown therein, sixrings of antennas of 32 antennas each are provided. The chamber 860 is195 mm deep and the six various rings are spaced 30 mm apart such thatthe first ring (the ring nearest the opening of the chamber 860, whichis shown at the top in FIG. 9) is positioned 15 mm from the edge of theopening and the sixth ring (the ring closest to the bottom of chamber860) is positioned 30 mm from the bottom. The interior of thecylindrical chamber has a radius of 145 mm (diameter of 290 mm) and theexterior of the chamber has a radius of 155 mm (diameter of 310 mm). Itwill be appreciated that other numbers of rings, numbers of antennas perring, spacing between rings, spacing between first ring and opening,spacing between final ring and chamber bottom, depth of chamber,interior and exterior radius/diameter of the cylinder, and otherdimensions may be varied as desired.

In alternative embodiments, imaging chambers of other topologies may beutilized. In this regard, FIGS. 10A and 10B are side views of analternative spherical electromagnetic tomography (EMT) imaging chamber760, shown without and with antennas 765 installed therein, for use inan imaging chamber system in accordance with one or more preferredembodiments of the present invention. In the illustrated embodiment, theantennas 765 are waveguide antennas, but it will be appreciated thatother types of antennas, such as slot antennas, may be used instead. Inthe illustrated embodiment, the spherical imaging chamber 160 includes177 antennas 765, each with an adaptor, that are arranged in eight tiersof varying numbers of antennas each plus pole antenna. In someembodiments, the antenna adaptors are linked to a box of 177specifically designed printed circuit boards (PCBs) by semi-rigidcoaxial cables, or are integrated directly into PCBs, wherein the PCBsprovide control and data processing functionality. However, in someembodiments, other physical implementations are possible; for example,as described below, the number of separate control devices may bereduced through the use of sequential, rather than simultaneous,operation of the antennas.

The antennas are preferably designed to produce a particular pattern ofradiation in order to improve the image reconstruction process. In thisregard, FIG. 11 is a graphical representation of a preferred radiationpattern 250 for use in one or more preferred embodiments of the presentinvention. As shown therein, a desired radiation pattern 250 may beproduced in both the x-y plane and the y-z plane using eitherspecifically-designed slotted antennas 165 or specifically-designedwaveguide antennas 765.

The antennas 165,765 preferably operate simultaneously, wherein eachantenna 165,765 is integrated or connected to its own transceiver andsignal analyzer. In this regard, FIG. 12 is a simplified block diagramof hardware 200 for simultaneous antenna operation in an EMT imagingchamber 160,760. Using this approach, when any one of the antennas istransmitting, the signals received at all of the other antennas aremeasured simultaneously. With well-designed control functionality,transceiver modules are synchronized, and resulting data 220 from thetransmission/reception process is easily organized and distributed tothe Data/image Processing Center 230.

In some embodiments, it may be possible to use a sequential or“switching” approach such as that described in the aforementioned U.S.Pat. No. 9,414,749. Such an approach is shown as an alternativeembodiment in FIG. 13, which is a simplified block diagram of hardware800 for sequential antenna operation in an EMT imaging chamber 160,760.As shown therein, a single control unit 840 with radio frequencytransceiver and signal analyzer 840 is connected to a switch matrix 850that manages access to the antennas 165,765. It is generally preferredthat the signal analyzer 840 is a vector network analyzer (VNA). Theswitch matrix 850 conventionally utilizes a time-division approach,wherein each antenna 165,175 is connected to the same electroniccontrols but data is saved in different time slots. However, when thisconventional 2-port VNA/switch matrix/time-division strategy isutilized, it suffers from various problems that are believed to beovercome through the use of a simultaneous approach such as that shownin FIG. 12. This may be understood as follows.

When imaging a human brain, it is generally useful, and often evennecessary, to have a fairly large number of antennas (for example, 177or 192 in the various specific embodiments illustrated herein). Largenumbers of antennas likewise require an increase in the size of theswitch matrix 850. Unfortunately, these switches are relatively largeand have fixed physical dimensions, and their size and weight has asubstantial effect on the overall size and weight of the system. In thesimultaneous approach, by contrast, the switch matrix 850 is notnecessary. Instead, integrating such circuitry with each antenna(thereby avoiding the need for a switch matrix) improves technicalspecifications of the system (such as reducing data acquisition timefrom tens of minutes to milliseconds, effectively improvingsignal-to-noise ratio by avoiding movement artifacts of live biologicalobjects during the resulting short (millisecond) data acquisition time,and allowing for circulation-gated imaging) and reduces the weight anddimensions of the system by at least a factor of two.

Another drawback to the sequential approach is a lack of scalability. Ifadditional antennas are desired (for greater precision or the like), theswitch matrix must be redesigned with ever-increasing complexity. In thesimultaneous approach, if additional antennas are desired, they aresimply added.

It will also be appreciated that the dielectric properties of both thematching media and the human brain itself are highly attenuative. (Asfurther discussed hereinbelow, in at least some preferred embodiments,the matching media is formulated so as to have dielectric propertiessimilar to the “average” dielectric properties of a human brain.) Thus,as the signals are sent and received, there is a decrease in magnitudeof the wave properties as they travel due to absorption and scatteringof the signals. This, in turn, requires the use of lengthy measurementtimes (e.g., 10 milliseconds) in order to achieve a good signal-to-noise(S/N) ratio. When these measurements are carried out sequentially, aseparate measurement must be carried out for each combination oftransmitting and receiving antenna. Thus, for example, if all possiblemeasurements are made in a system in which 192 antennas are used, thereare a total of 192×191 measurement periods which require a totalmeasurement time of 192×191×10 milliseconds, which totals more than 6minutes. Operation of the switch matrix to adjust control from one pairof antennas to another requires still further time. Unfortunately, it isdifficult if not impossible for the human body to remain completely freeof movement for 6 minutes or more, which means that taking measurementsover such a long period of time inevitably introduces additional“movement” noise into the results.

In the simultaneous approach, by contrast, the data acquisition timesare much shorter because measurements are made at all receiving antennassimultaneously. For example, if all possible measurements are made in asystem in which 192 antennas are used, then 191 measurements are madesimultaneously (in parallel) while each of the 192 antennas istransmitting. Assuming the measurement time remains the same (e.g., 10milliseconds), there are a total of only 192 measurement periods whichrequire a total measurement time of 192×10 milliseconds, which totalsonly about 2 seconds.

Overall, the simultaneous approach thus allows for considerably shorterdata acquisition times as compared to a sequential approach, reduces thesize and weight of the necessary hardware, provides greater scalability,and is better able to provide more measured components for thecomplex-valued tensors used in image reconstruction processes describedelsewhere herein.

In at least some embodiments, the radio frequency (RF) transceivercircuitry and related hardware may be implemented using asuperheterodyne technology-based architecture, wherein radio signals areconverted to/from a fixed intermediate frequency (IF) that can be moreconveniently processed than the original carrier frequency. In thisregard, FIG. 14 is a block diagram illustrating the application of asuperheterodyne architecture for use in the electromagnetic tomographicscanner 110. As shown therein, the control hardware 270 includescircuitry comprising an RF stage 272 that is connected to the antenna165,765, circuitry comprising an intermediate frequency (IF) stage 275,and a baseband (BB) data processing stage 278. The RF stage is connectedto the antenna 165,765. In at least some embodiments, the RF transceivercircuitry 270 has a transmit side and a receive side that arealternately connected to the antenna 165,765 using an RF switch 271.Power amplifiers 291 and low-noise amplifiers 292 are preferablyprovided in the transmit path and the receive path, respectively, inorder to address attenuation issues inherent with RF signals in braintissues. For example, at a frequency of 1 GHz, the mean value fordielectric attenuation of the brain is about 2.5 dB/cm.

The heart of a preferred RF transceiver 272 is a frequency synthesizerthat provides a high frequency carrier signal (e.g. 1 GHz) for theanalog modulation/demodulation process. Similarly, an IF carrier signalis modulated/demodulated using the back-end digital signal. Filtering,amplification, and other IF functions are likewise carried out in the IFstage 275, and signal/data conversion (DAC/ADC) and digital postprocessing are conducted in the baseband stage 278.

Notably, quadrature modulation is applied such that the IF signal hasboth in-phase and quadrature components. These two components allow forvector analysis, or the tracking of changes in both amplitude and phaseof the received signal. Furthermore, because the transmitter andreceiver share a common clock oscillator 290, amplitude and phase of thereceived signal can be determined with reference to the transmit signal.

Depending on the design of the antennas 165,765, the RF transceivercircuitry 272, and the control thereof, the interconnection might berealized by semi-rigid coaxial cables or printed strip lines. In apreferred embodiment, this is realized with a two-module PCB-basedimplementation of antennas and corresponding RF transceiver circuitry.In an example of such an arrangement, the necessary functionality forthe antennas 165,765 is implemented on a first module and the necessaryRF transceiver circuitry 272 is implemented on a second module, whereineach module includes a PCB that is about 40 sq. cm. in size, and themodules are interconnected via coaxial cables. By removing the switchmatrix technology and introducing PCB-based technology, significantweight and size reductions in hardware are obtained.

It will be appreciated that for simultaneous operation, the individualcontrollers must be synchronized. In this regard, FIG. 15 is a blockdiagram illustrating the application of a synchronized superheterodynearchitecture for use in the electromagnetic tomographic scanner 110. Asshown therein, the control hardware 300 includes a single control unit295 that provides functionality for an arbitrary number of antennacontrollers and their respective antennas. Such functionality mayinclude, for example, clock generation (including a common clockoscillator), synchronization, data collection, data processing, and datastorage/transfer. In at least some embodiments, the control unit 295 isimplemented separately (e.g., on a separate PCB) from the PCBscontaining the RF transceiver circuitry 272.

When dedicated RF transceiver circuitry 272 is utilized for each antenna165,765, performance variations between each of the transmitting (Tx) orreceiving (Rx) channels can be expected due to the imperfections ofmanufacturing and assembly. Therefore, an equalization technique,referred to as a calibration process, is desirable in order to quantifythe received signals relative to each other and thus compensate for suchvariations. In this regard, FIG. 16 is a flow diagram of an exemplarycalibration process 1500 for use in one or more preferred embodiments ofthe EMT system 100 shown in FIG. 3, although other approaches mayadditionally or alternatively be utilized. The exemplary calibrationprocess 1500 is preferably carried out under conditions similar to thosein which the system will actually be used, but without a patient beingpresent. During actual use, at least in some embodiments, the space inthe imaging chamber 160 around the patient's head is occupied with abackground or matching media. Thus, as a preliminary step 1505 in thecalibration process 1500, the imaging chamber 160 is first filled withthe appropriate matching media before carrying out the rest of theprocess 1500. In at least some embodiments, the open end of the imagingchamber 160 is covered with a lid to crudely mimic boundary conditions,prevent matching media from spilling from the chamber 160, and/or forother purposes.

The matching media is a fluid or gel that is used to addresselectromagnetic body-matching problems and/or other issues. In at leastsome embodiments, the matching liquid is a mixture of glycerol (Ph.Eur.), water and brine. In at least some preferred embodiments, thematching media is formulated so as to have dielectric permittivity(ϵ=ϵ′+jϵ″) that is similar to an averaged value of all brain tissues,i.e., the average of everything inside a skull. Thus, in those preferredembodiments, ϵ′=about 30 to 60 and ϵ′=about 15 to 25, and in at leastsome embodiments, ϵ′=about 40 to 45 and ϵ′=about 17 to 21. By using amatching media whose dielectric permittivity is so similar to thecollective average of the brain tissue, it is believed that an effect ofskull-shielding is minimized.

According to various aspects of the present invention, the imagingchamber 160 may be filled with a matching media in various ways. In someembodiments, technology such as that disclosed in the aforementionedU.S. Pat. No. 9,414,749 may be used. In some embodiments, the imagingchamber system 150 may be equipped to rotate at least the imagingchamber 160 upward such that gel may be loaded into the chamber 160. Inat least some of these embodiments, the imaging chamber 160 may berotated to a vertical orientation wherein the main axis thereof isoriented vertically. In this regard, FIG. 17 is a side view of themoveable imaging chamber system 150 of FIG. 3, shown after being rotatedto a vertical position. Such a position may be useful, for example, forloading matching media into the imaging chamber 160, calibrating thesystem, and/or measuring the empty field. Details of some preferablemethodologies for these steps are described elsewhere herein. Notably,in some embodiments, the imaging chamber 160 is not rotated fullyvertical.

With the matching media in place, a reference antenna 310 is preciselypositioned at the center of a ring R of N antennas. In this regard, FIG.18A is a schematic diagram of a reference antenna 310 temporarilypositioned in the center of an imaging chamber 160,760. The referenceantenna 310 may be positioned with the help of a specifically designedhigh tolerance antenna holder (for example a monopole antenna). Thereference antenna 310 is used to carry out two sets of measurements foreach of K frequencies of interest. In one set of measurements, with thereference antenna transmitting, data is measured as received at each ofthe N antennas in the ring R, as shown at step 1515. This can be done atall N antennas simultaneously (or less preferably, one at a time,sequentially). As shown in FIG. 18B, the reference antenna 310preferably has an omnidirectional radiation pattern, thereby permittingsimultaneous measurement at all receiving antennas 165. In the other setof measurements, with the Nth antenna 170 in the ring transmitting, datais measured as received at the reference antenna 310, as shown at step1520. In this regard, FIG. 18C is a schematic diagram of one antenna ofinterest 170 transmitting for purposes of measuring data received at thereference antenna 310. As shown at step 1525, the ring antenna ofinterest 170 is then incremented until steps 1515 and 1520 have beenrepeated for each antenna N in the ring R, and as shown at step 1530,this process is repeated for each desired frequency K. As shown at step1535, steps 1510-1530 (including repositioning the reference antenna)are then repeated for each of the other rings until calibration data hasbeen fully generated for all antennas, rings, and frequencies as shownat step 1540. (It will be appreciated that the flow diagram of FIG. 16is illustrative only and that these steps need not be carried out in thespecific order illustrated therein.) The calibration data thus obtainedis a complex-valued tensor with coefficients C_(i,j,k) ^(Exp,calibr).

FIG. 19 is an exemplary graphical representation of measured signalsreceived from the reference antenna 310 by various antennas 165 around aring. By measuring characteristics of the received signals, shown by thewhite points 320 on the graph, while the reference antenna istransmitting, the differences (i.e., imperfections) among the receivepaths are determined. Similarly, the differences among the transmitpaths are identified when the reference antenna is operating in thereceive mode while individual antennas 165 are transmitting.Mathematically, the matrix of calibration coefficients C_(i,j,k)^(Exp,calibr) that is thus constructed may then be applied to rawmeasured data during actual operation of the system.

After the calibration process 1500 has been completed, the process ofobtaining “raw” patient data may be carried out. The patient datageneration process starts with the imaging chamber 160 completely filledwith the matching medium, but no object inside. This empty fieldmeasurement is executed which results in a complex-valued tensor ofI×J×k components, where I is the number of transmitting antennas, J thenumber of receiving antennas and k the number of measured frequencies.This tensor is represented by S_(i,j,k) ^(meas,empty), the S-parametersfor the measured empty field for each pair of transmitting and receivingantennas i,j for each emitting frequency k. Next, as shown in FIGS. 4Aand 4B, the patient 108 and/or the scanner 110 are moved, positioned,and/or adjusted such that the patient's head 109 is positioned in thecorrect position inside the chamber 160. With the patient's head 109 inplace, the full field measurements are carried out, thereby producing atensor, represented by S_(i,j,k) ^(meas,full) corresponding to themeasured full field for each pair of transmitting and receiving antennasi,j for each emitting frequency k. A third tensor, represented byS_(i,j,k) ^(meas,scatt) and corresponding to the scattering caused bythe patient's head 109, may then be obtained from the algebraicsubtraction S_(i,j,k) ^(meas,scatt)=S_(i,j,k) ^(meas,full)−S_(i,j,k)^(meas,empty). The three complex-valued tensors S_(i,j,k) ^(meas,full),S_(i,j,k) ^(meas,empty), S_(i,j,k) ^(meas,scatt), containing theS-parameters for each pair of transmitting and receiving antennas foreach emitting frequency, and the calibration tensor C_(i,j,k)^(Exp,calibr), containing the calibration components for each pair oftransmitting and receiving antennas for each emitting frequency,comprise the primary input data sets for the image reconstructionalgorithms described below.

The boundary conditions when measuring the empty chamber containing onlymatching media (S_(i,j,k) ^(meas,empty)) are preferably as close aspossible to the boundary conditions when measuring the full chambercontaining an object such as a human head and the matching mediaS_(i,j,k) ^(meas,empty). However, as can be seen in (for example) FIG. 3and FIG. 4B, it will be appreciated that basic anatomy dictates thatwhen a patient's head is placed in the chamber for measurement, the restof the patient's body remains outside of the chamber. The portions ofthe patient's body that are outside the chamber typically include someor all of the patient's neck and lower portions of the patient's headitself. Notably, although outside the chamber, these portions(particularly including the lower portions of the patient's head 109 andneck) modify the boundary conditions for the electromagnetic fieldsmeasured inside the chamber as compared to when no human body 108 ispresent.

Thus, in at least some embodiments, use may be made of an apparatus,when measuring the empty chamber, to mimic the boundary conditions thatare present when measuring the full chamber. In this regard, FIG. 20A isa perspective view of a lid, including a frame 162 supporting a hollowboundary model 164, for use in at least some embodiments in mimickingthe part of the body 108 outside of the imaging chamber 160 during emptyfield measurements. As shown therein, the hollow boundary model 164roughly approximates the shape of the lower portion of a human head. Theframe 162, which is preferably rigid, includes a centrally locatedellipsoidal hole 163 through which the model 164 extends. In thisregard, FIG. 20B is a front view of the frame 162 of FIG. 20A. In use,the hollow boundary model 164 may be attached to the rigid frame 162 andthe lid may be installed across the opening of the imaging chamber 160.In this arrangement, the hollow boundary model 164 extends out of (awayfrom) the chamber 160, roughly mimicking the disposition of the lowerportion of a human head. When the interior of the model 164 (the portionfacing the interior of the chamber 160) is filled (at least partially,but preferably fully) with matching media, the matching media thusextends out of the imaging chamber 160 and is positioned in the areawhere the remainder of the head 109 and possibly the neck of the body108 would be located, as shown in FIG. 20C.

In some embodiments, the hollow boundary model 164 its own closed cavityso as to retain the matching media therein without escaping. In someembodiments, a closed cavity is created entirely by the model; in otherembodiments, the closed cavity is formed between the model 164 and afull (solid) lid having no ellipsoidal or other opening therein.

In some embodiments, the imaging chamber 160 is at least partiallytilted, or even inverted, so as to cause matching media to flow into orotherwise enter the interior of the hollow boundary model 164. In somesuch embodiments, the model 164 is sealed to the frame 162 and the lidis removably sealed to the imaging chamber 160 to prevent matching mediafrom escaping from the imaging chamber and/or the interior of the hollowboundary model 164. In other embodiments, sealing may not be necessary;for example, if the matching media is in the form of a gel or otherwisehas a consistency that does not flow readily, simple attachment of thelid to the imaging chamber may be sufficient to prevent escape of thematching media from the imaging chamber 160.

In various embodiments, the centrally located hole may take on shapesother than ellipsoidal, such as circular.

This additional feature to the invention better simulates the conditionsof the boundary antenna measurements. For example, reference is made toFIG. 21, which is a side cross-sectional view of the exemplarycylindrical EMT imaging chamber 860 of FIG. 9 but having a human headphantom 166, including a hemorrhagic stroke model 167, positionedtherein. Using this chamber 860, an EMT imaging process was carried outon the head phantom with stroke model using empty field measurementstaken in two different ways. The first set of empty field measurementswere taken on the empty imaging chamber 860 of FIG. 9 with a full(solid) lid covering the imaging chamber 860 and matching media fillingthe chamber 860 to the lid. The second set of empty field measurementwas taken on the empty imaging chamber 860 with the frame 162 and hollowboundary model 164 of FIG. 20A covering the imaging chamber 860 andmatching media filling the chamber 860 and the interior of the hollowboundary model 164. The full field measurements were then taken with thepartial frame 162 of FIG. 20B in place, matching media filling thechamber 860, and the head phantom with stroke model extending throughthe lid and into the chamber 860.

When 2D image reconstruction is carried out for various rings in basedon empty field measurements using the different boundary conditions, thebenefit of using the partial frame 162 and hollow boundary model 164 ofFIG. 20A is clear. FIGS. 22A and 22B are graphical representations ofthe result of 2D image reconstruction for the human head phantom 166inside the chamber 860 of FIG. 21 using the empty field measurementtaken with a full lid, wherein FIG. 22A represents the 2D imagereconstruction using output from the first antenna ring (the ringnearest the opening of the image chamber 860) and FIG. 22B representsthe 2D image reconstruction using output from the second antenna ring. Ashown in FIG. 22B, the reconstructed image from the second ring 169,which is not affected as strongly by the mismatched boundary conditionsbetween the empty field measurements and the full field measurementsbecause of its location relative to the exterior of the imaging chamber160, reveals the presence of the hemorrhagic stroke model 167. However,as shown in FIG. 22A, the reconstructed image from the first ring 168provides no indication of the hemorrhagic stroke model 167, due to themismatched boundary conditions of the empty measurement and the fullmeasurement.

On the other hand, when the boundary conditions of the empty fieldmeasurement and the full field measurement more closely match, evenimage reconstruction from the first antenna ring 168 identifies thehemorrhagic stroke model 167. In this regard, FIG. 22C is a graphicalrepresentation of the result of 2D image reconstruction for the samehuman head phantom 166, using the output from the first antenna ring168, but where the empty field measurement was carried out with thepartial frame 162 and hollow boundary model 164 of FIG. 20A covering theimaging chamber 860. As shown therein, the accuracy for the firstantenna ring 168 using the improved empty field measurement approach iscomparable to that of the second antenna ring 169 using the mismatchedboundary conditions.

In at least some embodiments, the measured data is validated locallyusing fast 2D image reconstruction algorithms are executed to obtain aplurality of 2D slices before full 3D image reconstruction is conductedremotely. This two stage process may be recommended due to the technicalchallenges inherent in conducting on-site image reconstruction (i.e. inthe control unit) for the full 3D vector problem due to significantnumerical complexity which generally necessitates a computing cluster.Thus, for 3D image reconstruction, the experimental data generally needsto be transferred to a computing system 128 that includes a morepowerful data processing unit than is generally available at the site ofthe electromagnetic tomographic scanner 110. On the other hand, 2D imagereconstruction requires considerably lower data processing capabilityand can be carried out locally. Local 2D image reconstruction can thusbe utilized for an initial validation of the measured data and apotential re-measurement of the data can be triggered immediately.Furthermore, the 2D slices (described below) can act as an initialcondition for the full 3D reconstruction, thus potentially reducing thenumber of necessary iterations when solving the inverse problem. Stillfurther, the initially reconstructed 2D slices do have considerablediagnostic power and provide valuable immediate information for thedecision makers. In this regard, it should be appreciated that althoughimage reconstruction based on the 2D solvers is possible, imagereconstruction based on the full 3D solvers improves the imagesquantitatively, and a reconstruction using full 3D vector is stronglypreferred in order to obtain a quantitative image in the whole volume.

In the 2D validation process, the measured data S_(i,j,k) ^(meas,full),S_(i,j,k) ^(meas,empty), after being collected as described above, isstored in the internal memory of a local database connected to theelectromagnetic tomographic scanner 110, and the scattered dataS_(i,j,k) ^(meas,scatt) is calculated and stored there as well. In someembodiments, the local database is provided in the local computer 129,which communicates directly with the electromagnetic tomographic scanner110, while in some embodiments, data from the electromagnetictomographic scanner 110 is stored in a local database (not shown), suchas a database managed by the hospital in which the electromagnetictomographic scanner 110 is located, and the local computer 129communicates with the local database. The local computer 129 is used toconduct measured data validation. In particular, using imagereconstruction procedures described below (and/or, at least someembodiments, in other patent documents), fast 2D image reconstructionalgorithms are executed to obtain a plurality of 2D slices, wherein a 2Dslice is obtained for each antenna ring. For example, if the chamber 160includes six antenna rings, six 2D slices—one for the permittivitydistribution in the plane of each ring—can be obtained.

After the validation procedure is complete, or in some cases concurrentwith such procedure, the data file is encrypted and sent, preferablytogether with a checksum, to the remote 3D image processing computersystem 128 located elsewhere in a hospital or other provider facility,at an IPC, or at another host. Transmission can be done using standardfile transfer protocols such as, without limitation, SFTP/SCP, a VPNtunnel, or the like, where the size of the image reconstruction data(typically, a 2×N×N matrix of complex values, corresponding to the emptyand full field, where N is the number of antennas) is usually lower than5 MB. On the remote 3D image processing computer system 128, the dataintegrity is checked via the checksum and processed with an imagereconstruction procedure such as the one detailed hereinbelow. Thereconstructed image together with the experimental data is preferablyalso stored in a redundant database. Then, it is converted into DICOMformat, encrypted and sent back to the decision makers.

At least for the purpose of maintaining patient confidentiality, aunique ID number may be generated for each data set and attached to thedata file. Notably, in at least some embodiments, it is not necessary toinclude any patient related information, such as name, gender, or thelike. Instead, using the unique ID number, the patient-relatedinformation can be added directly to the processed image in DICOM formatwhen later delivered to the decision maker as a reconstructed image.

Along with the hardware of the electromagnetic tomographic scanner 110,one or more specific methods is used to control the performance of thehardware in the scanner 110 during calibration, various measurements,data transfers, and other like procedure. In this regard, FIG. 23 is ahigh-level flow diagram of a 3D electromagnetic tomography imagereconstruction (EMTIR) method 1800 for use in an EMT system 100 inaccordance with one or more preferred embodiments of the presentinvention. The 3D EMTIR method 1800, which is generally carried out bythe 3D image processing computer system 128, is an iterative processwhere a convergence check (shown at step 1860) occurs after eachiteration through the various image reconstruction processes untilsuitable results are obtained and provided as the reconstructed imageoutput 1865.

As noted previously, the primary input to the EMTIR method 1800 is threecomplex-valued tensors 1805 comprising the S-parameters between antennapairs for each frequency. The number of tensor components is I×J×K,where I is the number of transmitting antennas, S_(i=1 to I), J is thenumber of receiving antennas S_(j=1 to J) and K is the number ofemitting frequencies f_(k=1 to K). The three tensors 1805 contain theS-parameters for the full field (when the measured object 109 is insidethe chamber 160), the empty field (when the chamber only contains thematching medium), and the scattered field (the field obtained due to thewave scattering phenomena from the measured object).

However, other inputs to the process 1800 are utilized as well. Otherinputs (not shown in FIG. 23) may include, for example, calibration data(as described previously), physical properties of the matching medium,geometry (topology) and physical properties of the imaging domain 21,and antenna properties. Another input to the EMTIR method 1800 is aninitial value for the dielectric permittivity distribution ϵ(x, y, z)1810 in the imaging domain 21. In some preferred embodiments, this valueis set as the matching medium permittivity value, ϵ⁰(x, y, z). In otherpreferred embodiments, additional prior information about the measuredobject 109, obtained from conventional imaging modalities applicable forhead imaging (such as but not limited to, MRI and CT), from fast 2Dslices reconstruction and/or known from previous scans of the sameobject, may be used to establish such value.

At block 1815, the direct problem is solved. Solving the direct probleminvolves the computation of the EM fields inside the imaging domain 21with dielectric permittivity ϵ(x, y, z) and the N transmitting antennas165 acting as electromagnetic sources. The solution of the directproblem in block 1815 results in three additional complex-valued tensorscontaining the S-parameters for the full, the empty and the scatteredfields (S_(ij,k) ^(sim,full), S_(ij,k) ^(sim,empty), S_(ij,k)^(sim,scatt) for each frequency) from the simulation point of view.Notably, the S-parameter tensor for the empty sim field, S_(ij,k)^(sim,empty), corresponds to the simulation of the chamber with matchingmedium but without the measured object 109. Therefore, as illustrated atstep 1820, this tensor is only computed at the start of the iterativeprocedure, and stored in the computer memory, as shown at block 1825. Atblock 1830 the S_(ij,k) ^(sim,full), S_(ij,k) ^(sim,scatt) are computedeach pass through the method.

The solution of the direct problem in block 1815, more specifically,consists of computing the EM fields inside the imaging domain 21 subjectto certain boundary conditions and modeling the antennas 165 as theelectromagnetic sources. Mathematically, this is performed through thenumerical solution of the Maxwell's equations, a set of coupled partialdifferential equations (PDEs) that give the relationship between theelectric and magnetic induction fields and the medium properties. Ingeneral, there is no analytical solution to these equations. Therefore,numerical algorithms are used to compute an approximate solution.Several well-known numerical methods exist including but not limited toFEM (Finite Element Methods) or FDTD (Finite-Difference Time-Domain).Numerical approximations of the electric and magnetic induction fieldsinside the imaging chamber 160 are made for every antenna 165 working astransmitter and receiver by solving Maxwell's equations inside theimaging domain 21 N times, where N is the total number of activeantennas, independent of whether the antenna is working as a transmitterand/or receiver.

Next, at step 1835 of the iterative process 1800, the inverse problem issolved. Solving the inverse problem involves modifying the dielectricpermittivity ϵ(x, y, z) in order to make the simulated S-parametertensors converge to the measured ones. Several mathematical algorithmsare available for application in this step 1835, including the Gradientmethod and the Newton-Kantorovich method. Further details of the inverseproblem solution process 1835 are described below, and additional oralternative details of direct and/or inverse problem solution processessuitable for use in some embodiments of the present invention may bedescribed in U.S. Pat. No. 9,072,449 to Semenov, issued Jul. 5, 2016 andentitled “WEARABLE/MAN-PORTABLE ELECTROMAGNETIC TOMOGRAPHIC IMAGING,”and U.S. Pat. No. 7,239,731 to Semenov et al., issued Jul. 3, 2007 andentitled “SYSTEM AND METHOD FOR NON-DESTRUCTIVE FUNCTIONAL IMAGING ANDMAPPING OF ELECTRICAL EXCITATION OF BIOLOGICAL TISSUES USINGELECTROMAGNETIC FIELD TOMOGRAPHY AND SPECTROSCOPY.” The relevantportions thereof are incorporated herein by reference.

As represented at step 1840, the option exists to incorporate patternrecognition and removal techniques into the EMTIR process 1800. Forexample, the distribution of increments resulting from block 1835, usedfor updating the dielectric permittivity, may be processed with patternrecognition and removal algorithms in order to remove undesireddisturbance effects and improve the quality of the reconstructed images.Suitable pattern recognition and removal techniques include methods ofEM Interference Pattern Recognition Tomography (EMIPRT) as disclosed inthe aforementioned International Application Serial No. PCT/US16/57254.Such methods may be applied as represented by step 1845.

Once the dielectric permittivity ϵ(x, y, z) is updated as shown at block1850, the value of the functional is computed at block 1855. The valueof functional corresponds to the difference between the actual(measured) values and the simulated values. If at step 1860 thefunctional value satisfies pre-defined criteria, which may includedefining a percentage value of the initial functional value, thenconvergence is said to have been reached, and the reconstructed image isobtained plotting the final dielectric permittivity distribution inblock 1865. Otherwise, appropriate portions of the procedure arerepeated iteratively until convergence is reached.

As noted previously, solving the inverse problem at block 1835 involvesmodifying the dielectric permittivity ϵ(x, y, z) in order to make thesimulated S-parameter tensors converge to the measured ones. Morespecifically, input is generated and used in the reconstruction of thepermittivity distribution ϵ({right arrow over (r)})≡ϵ(x, y, z)∈C insidethe chamber 160. The inverse problem solution is the permittivitydistribution which minimizes the discrepancy between measured data andsimulated data, or minimizes a given norm

$\begin{matrix}{\min\limits_{\epsilon}{{{S^{exp} - {S^{thy}\lbrack\epsilon\rbrack}}}.}} & (1)\end{matrix}$

The real-valued functional to be minimized is of the form

$\begin{matrix}{{{J\left\lbrack {\epsilon\left( \overset{\rightarrow}{r} \right)} \right\rbrack} = {\sum\limits_{k = 1}^{N_{f}}{w_{k}{\sum\limits_{i = 1}^{N_{Tx}}{\sum\limits_{j = 1}^{N_{Rx}}{❘{S_{ij}^{exp} - {S_{ij}^{thy}\left\lbrack {\epsilon\left( \overset{\rightarrow}{r} \right)} \right\rbrack}}❘}^{2}}}}}},} & (2)\end{matrix}$

where the S_(ij)(f_(k), ϵ({right arrow over (r)}))∈C are the measuredand theoretical scattering matrix elements which depend on the3-dimensional permittivity distribution ϵ({right arrow over (r)})≡ϵ(x,y, z)∈C in the imaging domain 21 and on the given frequency f_(k). Inthe functional (2), N_(f) is the number of frequencies, N_(Tx), is thenumber of transmitters, N_(Rx) is the number of receivers, and w_(k)∈Ris an additional factor to weight different frequency contributions inthe sum.

The scattering matrix elements are obtained from subtracting themeasured S_(ij) values of the empty chamber 160 from the values obtainedwhen an object is placed within the chamber,

S _(ij) ^(sct) ≡S _(ij) ^(full) −S _(ij) ^(empty)  (3)

In order to maximize the information about the scatterer in thefunctional, different normalizations can be used depending on the objectunder study, including, without limitation:

$\begin{matrix}{{S_{ijk} \equiv {\frac{S_{ijk}^{sct}}{S_{ijk}^{empty}}\ldots{antenna}}}‐{by}‐{antenna}} & \left( {4a} \right)\end{matrix}$ $\begin{matrix}{{S_{ijk} \equiv {\frac{S_{ijk}^{sct}}{S_{i,{{opp}(i)},k}^{empty}}\ldots{opposite}}}‐{antenna}} & \left( {4b} \right)\end{matrix}$ $\begin{matrix}{{S_{ijk} \equiv {\frac{S_{ijk}^{sct}}{\max\left( S_{ijk}^{empty} \right)}\ldots{maximum}}}‐{value}} & \left( {4c} \right)\end{matrix}$ $\begin{matrix}{{S_{ijk} \equiv {\frac{S_{ijk}^{sct}}{\min\left( S_{ijk}^{empty} \right)}\ldots{minimum}}}‐{value}} & \left( {4d} \right)\end{matrix}$

FIG. 24 is a graphical representation (rendered in a black-and-whiteversion and a color version) of an image reconstruction, for an object,using opposite-antenna normalization as defined in equation (4 b) above.FIG. 25 is a graphical representation (rendered in a black-and-whiteversion and a color version) of an image reconstruction for the sameobject as that of FIG. 24 but using antenna-by-antenna normalization asdefined in equation (4 a) above. In FIGS. 24 and 25, the object undertest is a high contrast shell 961 in the form of an elliptical cylinderhaving a small inhomogeneity 967 placed inside in a location that isoff-centered to the left side.

In both cases (i.e., with both types of normalization), the imagereconstruction process is in a relatively early iteration. Theelliptical shell 961 itself is visible in both cases. However, theinhomogeneity 967 is only visible in FIG. 25, which is the case usingantenna-by-antenna normalization. As shown in FIG. 24, the ring-typeartifacts present in the opposite-antenna normalization case preventreconstruction of the small inhomogeneity 967 during early iterations.In some embodiments, these ring-type artifacts may be removed using apattern removal techniques as described in the aforementionedInternational Application Serial No. PCT/US16/57254. However, theillustrated comparison demonstrates that antenna-by-antennanormalization may be used to minimize ring-type artifacts without suchadditional processing, resulting in the small object 967 inside the highcontrast shell 961 being more readily visible, particularly in earlyiterations of the image reconstruction process. This can be furtherenhanced through the use of a matching media formulated to havedielectric properties similar to the “average” dielectric properties ofa human brain, which helps minimize the effects of skull-shielding.Thus, the use of antenna-by-antenna normalization and/or proper amatching media with dielectric properties similar to the averagedielectric properties of a human brain can be considered, in at leastsome embodiments, as an alternative to the use of pattern removaltechniques and/or other additional processing techniques.

Furthermore, it will be appreciated that the antenna-by-antennanormalization acts as an intrinsic calibration. If the back-interactionfrom the head 109 or other object to the antennas 165,765 is weak, thecalibration coefficients are equal for the scattered and the emptyfield. In this case, they drop out:

$\begin{matrix}{{{S_{ij} \equiv \frac{C_{ij}^{sct}S_{ij}^{sct}}{C_{ij}^{empty}S_{ij}^{empty}}} = {\frac{C_{ij}^{empty}S_{ij}^{sct}}{C_{ij}^{empty}S_{ij}^{empty}} = \frac{S_{ij}^{sct}}{S_{ij}^{empty}}}},} & (5)\end{matrix}$

and no calibration is necessary. However, this assumption is no longervalid if the antennas 165,765 are very close to the object 109.

The complex-valued gradient of the functional (2) is obtained via thefunctional derivative of J with respect to ϵ({right arrow over (r)}) andis given by

$\begin{matrix}{{{J_{grad}\left( \overset{\rightarrow}{r} \right)} \equiv {\frac{\delta}{{\delta\epsilon}\left( \overset{\rightarrow}{r} \right)}{J\left\lbrack {\epsilon\left( \overset{\rightarrow}{r} \right)} \right\rbrack}}} = {\sum\limits_{k = 1}^{N_{f}}{w_{k}{\sum\limits_{i = 1}^{N_{Tx}}{\sum\limits_{j = 1}^{N_{Rx}}{{conj}\left( {\overset{\rightarrow}{E_{l}}{\left( {f_{k},\overset{\rightarrow}{r}} \right) \cdot \overset{\rightarrow}{E_{J}}}\left( {f_{k},\overset{\rightarrow}{r}} \right)} \right)\left( {S_{ij}^{exp} - S_{ij}^{thy}} \right)}}}}}} & (6)\end{matrix}$

where {right arrow over (E)}_(i,j)(f_(k), {right arrow over (r)}) arethe simulated EM fields transmitted from antenna i and j, respectively,and conj denotes complex conjugation. It is noted that a constant factor(2π/λ_(k))² has been absorbed into w_(k).

Finally, the permittivity contribution in the imaging domain 21 isobtained via the iterative process

ϵ({right arrow over (r)})^(n+1)=ϵ({right arrow over (r)})^(n) −h ^(n) J_(grad) ^(n)({right arrow over (r)})  (7)

where h^(n)∈R denotes the real-valued step-size at a given iteration n.

The optimization problem to minimize the functional in order toreconstruct the permittivity distribution is an ill-posed problembecause the number of measured values is much smaller than the number ofunknowns of the inverse problem. Therefore, a regularization procedureis preferably used. One of the possible options is the classicalTikhonov regularization method, which is robust and easy to implement.

The resulting image can be used for any of a variety of purposes,including for assessment, diagnosis, 4D dynamic fused electromagnetictomography, monitoring viability and functional conditions using suchEMT, and others involving any functional or pathological conditions ofbrain tissue, including but not limited to, ischemia, hypoxia, bloodcontent, acute and chronic stroke and differentiation of stroke type(such as ischemic or hemorrhagic), edema, traumatic brain injuries(TBI), tumors and differentiation of tumor type, and the like.

Based on the foregoing information, it will be readily understood bythose persons skilled in the art that the present invention issusceptible of broad utility and application. Many embodiments andadaptations of the present invention other than those specificallydescribed herein, as well as many variations, modifications, andequivalent arrangements, will be apparent from or reasonably suggestedby the present invention and the foregoing descriptions thereof, withoutdeparting from the substance or scope of the present invention.

Accordingly, while the present invention has been described herein indetail in relation to one or more preferred embodiments, it is to beunderstood that this disclosure is only illustrative and exemplary ofthe present invention and is made merely for the purpose of providing afull and enabling disclosure of the invention. The foregoing disclosureis not intended to be construed to limit the present invention orotherwise exclude any such other embodiments, adaptations, variations,modifications or equivalent arrangements; the present invention beinglimited only by the claims appended hereto and the equivalents thereof.

What is claimed is:
 1. An electromagnetic tomographic scanner for use in imaging a live human body part, comprising: an imaging chamber, supported on a base, that defines an imaging domain in which at least a portion of a live human body part is received, wherein the imaging chamber has an open end that may be covered by a lid; a plurality of antennas, arranged in at least one ring, that are supported by the imaging chamber and encircle the imaging domain, wherein the antennas are controllable to receive a transmitted electromagnetic signal after passing through the imaging domain; a controller for controlling one or more of the plurality of antennas; a lid that is attachable to the open end of the imaging chamber, wherein the lid includes a hollow boundary model that mimics the anatomy of a portion of the human, extending away from the imaging domain of the imaging chamber, and wherein the portion of the human whose anatomy is mimicked is the portion of the human that is expected to be disposed outside of the imaging domain when the portion of the live human body part is received in the imaging domain; and a quantity of a matching media, the matching media filling an interior of the hollow boundary model while an empty field measurement is carried out via the at least one ring of antennas.
 2. The electromagnetic tomographic scanner of claim 1, wherein the hollow boundary model mimics the anatomy of a portion of the head of the human.
 3. The electromagnetic tomographic scanner of claim 2, wherein the hollow boundary model mimics the anatomy of a lower portion of the human head.
 4. The electromagnetic tomographic scanner of claim 2, wherein the lid includes a frame having a central opening that is surrounded by the hollow boundary model such that when the lid is attached to the open end of the imaging chamber, the interior of the hollow boundary model is in fluid communication with the imaging domain.
 5. The electromagnetic tomographic scanner of claim 4, wherein the central opening is ellipsoidal.
 6. The electromagnetic tomographic scanner of claim 4, wherein the frame is rigid.
 7. The electromagnetic tomographic scanner of claim 2, wherein the lid is a full lid and wherein the hollow boundary model defines a separate interior cavity, not in fluid communication with the imaging domain, that is filled by the matching media.
 8. The electromagnetic tomographic scanner of claim 2, wherein the matching media is a liquid.
 9. The electromagnetic tomographic scanner of claim 2, wherein the lid is temporarily sealed to the open end of the imaging chamber while the empty field measurement is carried out.
 10. The electromagnetic tomographic scanner of claim 9, wherein the matching media is a liquid, and wherein the temporary seal between the lid and the open end of the imaging chamber prevents leakage of the matching media from between the imaging chamber and the lid.
 11. The electromagnetic tomographic scanner of claim 2, wherein the matching media is a gel.
 12. The electromagnetic tomographic scanner of claim 11, wherein the lid is attached, but not necessarily sealed, to the open end of the imaging chamber while the empty field measurement is carried out, and wherein the consistency of the gel prevents leakage from between the imaging chamber and the lid.
 13. The electromagnetic tomographic scanner of claim 2, wherein the imaging chamber is at least partially tilted, while the empty field measurement is carried out, such that matching media is caused to flow into the interior of the hollow boundary model.
 14. The electromagnetic tomographic scanner of claim 2, wherein the imaging chamber is adjustable during use from a vertical orientation, wherein the open end of the imaging chamber faces upward, to a horizontal orientation, wherein the open end of the imaging chamber faces sideward.
 15. A method of conducting electromagnetic tomography for imaging a human head, comprising: providing an imaging chamber, supported on a base, that defines an imaging domain in which at least a portion of a live human body part may be received, wherein the imaging chamber has an open end, wherein the imaging chamber supports a plurality of antennas, arranged in at least one ring, that encircle the imaging domain, and wherein each antenna may be controlled by a controller; temporarily attaching a lid to the open end of the imaging chamber, wherein the lid includes a hollow boundary model that mimics the anatomy of a portion of the human, extending away from the imaging domain of the imaging chamber, and wherein the portion of the human whose anatomy is mimicked is the portion of the human that is expected to be disposed outside of the imaging domain when the human's head is received in the imaging domain; filling an interior of the hollow boundary model with a matching media; without the human in the imaging domain, carrying out a process of empty field measurement by transmitting electromagnetic signals and receiving them, after passing through the imaging domain, at each of a plurality of the antennas in the at least one ring; with the lid in a removed state, positioning at least a portion of a live human body part through the opening in the end of the imaging chamber, and, subsequently, carrying out a process of full field measurement by transmitting electromagnetic signals and receiving them, after passing through the imaging domain, at each of a plurality of the antennas in the at least one ring; and carrying out an electromagnetic tomography image reconstruction process using both the empty field measurements and the full field measurements.
 16. The method of claim 15, wherein the hollow boundary model mimics the anatomy of a portion of the head of the human.
 17. The method of claim 16, further comprising a step of filling the imaging domain of the imaging chamber with a further quantity of the matching media, and wherein the imaging domain of the imaging chamber contains the matching media during both the empty field measurement process and the full field measurement process.
 18. The method of claim 17, wherein the hollow boundary model is a closed cavity that is not in fluid communication with the imaging domain of the imaging chamber.
 19. The method of claim 17, wherein the hollow boundary model is open such that the interior of the hollow boundary model is in fluid communication with the imaging domain of the imaging chamber when the lid is temporarily attached to the open end of the imaging chamber.
 20. The method of claim 16, wherein the lid includes a frame having a central opening that is surrounded by the hollow boundary model, and wherein the step of temporarily attaching a lid to the open end of the imaging chamber includes attaching the lid such that the interior of the hollow boundary model is in fluid communication with the imaging domain.
 21. The method of claim 16, wherein the lid is a full lid, wherein the hollow boundary model defines a separate interior cavity, wherein filling an interior of the hollow boundary model with a matching media includes filling the separate interior cavity with a matching media, and wherein the step of temporarily attaching a lid to the open end of the imaging chamber includes attaching the lid such that the separate interior cavity of the hollow boundary model is not in fluid communication with the imaging domain.
 22. The method of claim 16, wherein the step of temporarily attaching a lid to the open end of the imaging chamber includes temporarily sealing the lid to the open end of the imaging chamber, and wherein the step of carrying out a process of empty field measurement is carried out while the lid is temporarily sealed to the open end of the imaging chamber.
 23. The method of claim 16, further comprising a step of adjusting the imaging chamber, during use, from a vertical orientation, wherein the open end of the imaging chamber faces upward, to a horizontal orientation, wherein the open end of the imaging chamber faces sideward.
 24. A method of conducting electromagnetic tomography for imaging a human head, comprising: providing an imaging chamber, supported on a base, that defines an imaging domain in which at least a portion of a human head may be received, wherein the imaging chamber has an open end, wherein the imaging chamber supports at least one ring of antennas that encircles the imaging domain, and wherein each antenna may be controlled by a controller; without the human in the imaging domain, carrying out a process of empty field measurement by transmitting electromagnetic signals from respective antennas and receiving them, after passing through the imaging domain, at each of a plurality of the antennas in the at least one ring; storing the empty field measurements; producing a first tensor, represented by S_(i,j) ^(meas,empty), corresponding to the measured empty field for each pair of transmitting and receiving antennas i,j; positioning a human head through the opening in the end of the imaging chamber; with the head of the human positioned through the open end of the imaging chamber such that at least a portion of the human's brain is disposed in the imaging domain, carrying out a process of full field measurement by transmitting electromagnetic signals from respective antennas and receiving them, after passing through the imaging domain, at each of a plurality of the antennas in the at least one ring, wherein the measurements; producing a second tensor, represented by S_(i,j) ^(meas,full), corresponding to the measured full field for each pair of transmitting and receiving antennas i,j; producing a third tensor, represented by S_(i,j,k) ^(meas,sct) corresponding to the scattering caused by the human's head via the algebraic subtraction S_(i,j,k) ^(meas,sct)=S_(i,j,k) ^(meas,full)−S_(i,j,k) ^(meas,empty); using at least the first, second, and third tensors, carrying out an iterative process involving the solving of a direct problem, the solving of an inverse problem, the calculation of updated dielectric permittivity values corresponding to the human's brain in the imaging domain, and the computation of a functional that is evaluated for convergence to predetermined criteria, wherein an antenna-by-antenna normalization is utilized in the functional such that ${S_{ij} \equiv \frac{S_{ij}^{sct}}{S_{ij}^{empty}}};$ and when convergence is achieved, producing a reconstructed image of a portion of the human's brain by plotting a final dielectric permittivity distribution.
 25. The method of claim 24, wherein: the method further comprises a step of formulating a matching media to have a dielectric permittivity of (ϵ=ϵ′+jϵ″) such that ϵ′ is in the range of about 40 to 45 and ϵ″ is in the range of about 17 to 21, wherein the electromagnetic tomography system includes an electromagnetic tomographic scanner and an image processing computer system, and wherein the electromagnetic tomographic scanner includes an imaging chamber, supported on a base, that includes an open end and that defines an imaging domain; the method further comprises at least partially filling the imaging chamber with the matching media; and the step of carrying out a process of full field measurement with the head of the human positioned through the open end of the imaging chamber is executed with the imaging chamber at least partially filled with the matching media. 